package org.djutils.swing.multislider;
   
   import java.awt.BorderLayout;
   import java.awt.Component;
   import java.awt.Dimension;
   import java.awt.Font;
   import java.awt.Graphics;
   import java.awt.Point;
   import java.awt.event.ComponentAdapter;
  import java.awt.event.ComponentEvent;
  import java.awt.event.MouseEvent;
  import java.awt.event.MouseListener;
  import java.awt.event.MouseMotionAdapter;
  import java.util.Dictionary;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Map;
  
  import javax.swing.BoxLayout;
  import javax.swing.JComponent;
  import javax.swing.JLabel;
  import javax.swing.JPanel;
  import javax.swing.JSlider;
  import javax.swing.OverlayLayout;
  import javax.swing.SwingConstants;
  import javax.swing.SwingUtilities;
  import javax.swing.event.ChangeEvent;
  import javax.swing.event.ChangeListener;
  import javax.swing.plaf.SliderUI;
  import javax.swing.plaf.basic.BasicSliderUI;
  
  import org.djutils.exceptions.Throw;
  
  /**
   * The {@code AbstractMultiSlider} forms the base of implementing a slider with multiple thumbs. The AbstractMultiSlider is
   * implemented by drawing a number of sliders on top of each other using an Swing {@code OverlayManager}, and passing the mouse
   * events from a glass pane on top to the correct slider(s). The class is a {@code ChangeListener} to listen to the changes of
   * individual sliders underneath.
   * <p>
   * Several models exist to indicate whether thumbs can pass each other or not, or be on top of each other or not.
   * </p>
   * <p>
   * The {@code AbstractMultiSlider} stores all values internally as int. Only when getting or setting values (or, e.g., the
   * minimum or maximum), the generic type T is used.
   * </p>
   * <p>
   * Copyright (c) 2024-2025 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://djutils.org" target="_blank"> https://djutils.org</a>. The DJUTILS project is
   * distributed under a three-clause BSD-style license, which can be found at
   * <a href="https://djutils.org/docs/license.html" target="_blank"> https://djutils.org/docs/license.html</a>.
   * </p>
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @param <T> the type of values that the {@code AbstractMultiSlider} stores and returns
   */
  public abstract class AbstractMultiSlider<T> extends JComponent
  {
      /** */
      private static final long serialVersionUID = 1L;
  
      /** the sliders that are stacked on top of each other. */
      private JSlider[] sliders;
  
      /** the current slider number in process (e.g., drag operation, mouse down). */
      private transient int busySlider = -1;
  
      /** whether an operation is busy or not. */
      private transient boolean busy = false;
  
      /** the 'glass pane' on top of the sliders to dispatch the mouse clicks and drags to the correct slider. */
      private final DispatcherPane dispatcherPane;
  
      /** the panel in which the thumb labels can be drawn if this is wanted. */
      private final LabelPanel labelPanel;
  
      /** the initial index values of the labels for the reset function. */
      private final int[] initialIndexValues;
  
      /** the last known index values of the labels for the state change function. */
      private final int[] lastIndexValues;
  
      /** the labels per thumb (per underlying slider). */
      private final Map<Integer, String> thumbLabels = new HashMap<>();
  
      /** whether we draw thumb labels or not. */
      private boolean drawThumbLabels = false;
  
      /** the track size lowest pixel (to calculate width for horizontal slider; height for vertical slider). */
      private int trackSizeLoPx;
  
      /** the track size highest pixel (to calculate width for horizontal slider; height for vertical slider). */
      private int trackSizeHiPx;
  
      /** MultiSlider restriction on passing. */
      private boolean passing = false;
  
      /** MultiSlider restriction on overlap. */
      private boolean overlap = true;
  
      /** busy testing whether the state change of an underlying slider is okay, to avoid stack overflow. */
     private boolean testingStateChange = false;
 
     /**
      * Only one <code>ChangeEvent</code> is needed for the {@code MultiSlider} since the event's only (read-only) state is the
      * source property. The source of events generated here is always "this". The event is created the first time that an event
      * notification is fired.
      */
     private transient ChangeEvent changeEvent = null;
 
     /**
      * Creates a slider with the specified orientation and the specified minimum, maximum, and initial values. The orientation
      * can be either horizontal or vertical.
      * @param minIndex the minimum index value of the slider
      * @param maxIndex the maximum index value of the slider
      * @param horizontal the orientation of the slider; true for horizontal, false for vertical
      * @param initialIndexValues the initial index values of the thumbs of the slider
      * @throws IllegalArgumentException if initial values are outside the min-max range, or if the number of thumbs is 0, or
      *             when the values are not in increasing order (which is important for restricting passing and overlap)
      */
     public AbstractMultiSlider(final int minIndex, final int maxIndex, final boolean horizontal,
             final int... initialIndexValues)
     {
         Throw.when(initialIndexValues.length == 0, IllegalArgumentException.class, "the number of thumbs cannot be zero");
         Throw.when(minIndex >= maxIndex, IllegalArgumentException.class, "min should be less than max");
         for (int i = 0; i < initialIndexValues.length; i++)
         {
             Throw.when(initialIndexValues[i] < minIndex || initialIndexValues[i] > maxIndex, IllegalArgumentException.class,
                     "all initial value should be between min and max (inclusive)");
             Throw.when(i > 0 && initialIndexValues[i] < initialIndexValues[i - 1], IllegalArgumentException.class,
                     "all initial value should be in increasing order or overlap");
         }
 
         // store the initial value array in a safe copy
         this.initialIndexValues = new int[initialIndexValues.length];
         this.lastIndexValues = new int[initialIndexValues.length];
 
         // based on the orientation, add a JPanel with two subpanels: one for the labels, and one for the sliders
         setLayout(new BorderLayout());
         JPanel topPanel = new JPanel();
         topPanel.setLayout(new BoxLayout(topPanel, horizontal ? BoxLayout.Y_AXIS : BoxLayout.X_AXIS));
         topPanel.setOpaque(false);
         add(topPanel, horizontal ? BorderLayout.NORTH : BorderLayout.WEST);
 
         // create the label panel
         this.labelPanel = new LabelPanel(this);
         this.labelPanel.setLayout(new BorderLayout());
         this.labelPanel.setPreferredSize(new Dimension(1000, 0));
         this.labelPanel.setOpaque(false);
         topPanel.add(this.labelPanel);
 
         // create the slider panel
         JPanel sliderPanel = new JPanel();
         sliderPanel.setOpaque(false);
         topPanel.add(sliderPanel);
 
         // put a glass pane on top that dispatches the mouse event to all panes
         this.dispatcherPane = new DispatcherPane(this);
         sliderPanel.add(this.dispatcherPane);
 
         // make the sliders and show them. Slider 0 at the bottom. This one will get ticks, etc.
         sliderPanel.setLayout(new OverlayLayout(sliderPanel));
         this.sliders = new JSlider[initialIndexValues.length];
         for (int i = initialIndexValues.length - 1; i >= 0; i--)
         {
             this.initialIndexValues[i] = initialIndexValues[i]; // create copy
             this.lastIndexValues[i] = initialIndexValues[i];
             var slider = new JSlider(horizontal ? SwingConstants.HORIZONTAL : SwingConstants.VERTICAL, minIndex, maxIndex,
                     initialIndexValues[i]);
             this.sliders[i] = slider;
             slider.setOpaque(false);
             slider.setPaintTrack(i == 0);
             sliderPanel.add(slider);
 
             // ensure movability of the slider by setting it again
             slider.setValue(initialIndexValues[i]);
 
             // set the initial labels (issue #71)
             this.thumbLabels.put(i, "");
         }
 
         this.dispatcherPane.setPreferredSize(new Dimension(this.sliders[0].getSize()));
         calculateTrackSize();
 
         // listen to resize events to (re)set the track width or height
         addComponentListener(new ComponentAdapter()
         {
             @Override
             public void componentResized(final ComponentEvent e)
             {
                 super.componentResized(e);
                 AbstractMultiSlider.this.setUI(getUI());
                 calculateTrackSize();
                 AbstractMultiSlider.this.dispatcherPane.revalidate();
                 AbstractMultiSlider.this.labelPanel.revalidate();
                 AbstractMultiSlider.this.labelPanel.repaint();
             }
         });
 
         // listen to state changes of underlying sliders and check if restrictions are met
         for (int i = 0; i < this.sliders.length; i++)
         {
             final int index = i;
             this.sliders[index].addChangeListener(new ChangeListener()
             {
                 @Override
                 public void stateChanged(final ChangeEvent e)
                 {
                     if (!AbstractMultiSlider.this.testingStateChange)
                     {
                         AbstractMultiSlider.this.testingStateChange = true;
                         checkRestrictions(index);
                         AbstractMultiSlider.this.testingStateChange = false;
                     }
                     AbstractMultiSlider.this.fireStateChanged();
                 }
             });
         }
 
         invalidate();
     }
 
     /**
      * Return the individual sliders, where slider[0] contains the formatting.
      * @return the individual sliders
      */
     protected JSlider[] getSliders()
     {
         return this.sliders;
     }
 
     /**
      * Return an individual slider with index i.
      * @param i the index for which to retrieve the slider
      * @return the individual slider with index i
      */
     public JSlider getSlider(final int i)
     {
         return this.sliders[i];
     }
 
     /**
      * Return the number of thumbs on this multislider.
      * @return the number of thumbs on this multislider
      */
     public int getNumberOfThumbs()
     {
         return this.sliders.length;
     }
 
     /**
      * Indicate that slider i is busy (e.g., mouse-down or a drag operation).
      * @param i the slider number that is busy
      */
     protected void setBusySlider(final int i)
     {
         this.busySlider = i;
     }
 
     /**
      * Return whether slider i is busy (e.g., mouse-down or a drag operation).
      * @param i the slider number to check
      * @return whether slier i is busy or not
      */
     protected boolean isBusySlider(final int i)
     {
         return this.busySlider == i;
     }
 
     /**
      * Return which slider is busy (e.g., mouse-down or a drag operation). The function returns -1 if no slider is busy.
      * @return the slider number of the busy slider, or -1 if no slider is busy with an action
      */
     protected int getBusySlider()
     {
         return this.busySlider;
     }
 
     /**
      * Return whether one of the sliders is busy (e.g., mouse-down or a drag operation). Note that the 'busy' flag is set BEFORE
      * the mouse event (e.g., mouse released, mouse exited) is handled. This means that when 'busy' is true, no operation is
      * taking place.
      * @return whether one of the sliders is busy or not
      */
     public boolean isBusy()
     {
         return this.busy;
     }
 
     /**
      * Set whether one of the sliders is busy (e.g., mouse-down or a drag operation). Note that the 'busy' flag has to be set
      * BEFORE the mouse event (e.g., mouse released, mouse exited) is handled. This means that when 'busy' is true, no operation
      * is taking place.
      * @param busy set whether one of the sliders is busy or not
      */
     protected void setBusy(final boolean busy)
     {
         this.busy = busy;
     }
 
     /**
      * Reset the slider values to the initial values.
      */
     public void resetToInitialValues()
     {
         for (int i = 0; i < this.sliders.length; i++)
         {
             this.sliders[i].setValue(this.initialIndexValues[i]);
             this.sliders[i].invalidate();
             this.sliders[i].repaint();
         }
         fireFinalValueChanged();
         invalidate();
         repaint();
     }
 
     /**
      * Return the label panel in which thumb labels can be drawn. The labels move with the thumbs.
      * @return the label panel in which thumb labels can be drawn
      */
     protected LabelPanel getLabelPanel()
     {
         return this.labelPanel;
     }
 
     /**
      * Set the thumb label for thumb i to the given label.
      * @param i the thumb number
      * @param label the label to display
      * @throws IndexOutOfBoundsException when thumb number is out of bounds
      */
     public void setThumbLabel(final int i, final String label)
     {
         Throw.when(i < 0 || i >= getNumberOfThumbs(), IndexOutOfBoundsException.class, "thumb number %d is out of bounds", i);
         this.thumbLabels.put(i, label);
         invalidate();
     }
 
     /**
      * Get the thumb label for thumb i.
      * @param i the thumb number
      * @return the label to display
      * @throws IndexOutOfBoundsException when thumb number is out of bounds
      */
     public String getThumbLabel(final int i)
     {
         Throw.when(i < 0 || i >= getNumberOfThumbs(), IndexOutOfBoundsException.class, "thumb number %d is out of bounds", i);
         return this.thumbLabels.get(i);
     }
 
     /**
      * Turn the thumb label display on or off.
      * @param b whether the thumbs are displayed or not
      * @param sizePx the height (for a horizontal slider) or width (for a vertical slider) of the label panel in pixels
      */
     public void setDrawThumbLabels(final boolean b, final int sizePx)
     {
         calculateTrackSize();
         JSlider js = getSlider(0);
         this.drawThumbLabels = b;
         if (b)
         {
             if (isHorizontal())
             {
                 this.labelPanel.setPreferredSize(new Dimension(js.getWidth(), sizePx));
             }
             else
             {
                 this.labelPanel.setPreferredSize(new Dimension(sizePx, js.getHeight()));
             }
         }
         else
         {
             if (isHorizontal())
             {
                 this.labelPanel.setPreferredSize(new Dimension(js.getWidth(), 0));
             }
             else
             {
                 this.labelPanel.setPreferredSize(new Dimension(0, js.getHeight()));
             }
         }
         this.labelPanel.revalidate();
         revalidate();
     }
 
     /**
      * Return whether thumb label display on or off.
      * @return whether the thumbs are displayed or not
      */
     public boolean isDrawThumbLabels()
     {
         return this.drawThumbLabels;
     }
 
     /**
      * Recalculate the track size (width for horizontal slider; height for vertical slider) after a resize operation.
      */
     protected void calculateTrackSize()
     {
         JSlider js = getSlider(0);
         BasicSliderUI ui = (BasicSliderUI) js.getUI();
         int loValue = getInverted() ? js.getMaximum() : js.getMinimum();
         int hiValue = getInverted() ? js.getMinimum() : js.getMaximum();
         if (isHorizontal())
         {
             this.trackSizeLoPx = 0;
             this.trackSizeHiPx = js.getWidth();
             int i = 0;
             while (i < js.getWidth() && ui.valueForXPosition(i) == loValue)
             {
                 this.trackSizeLoPx = i++;
             }
             i = js.getWidth();
             while (i >= 0 && ui.valueForXPosition(i) == hiValue)
             {
                 this.trackSizeHiPx = i--;
             }
         }
         else
         {
             this.trackSizeLoPx = 0;
             this.trackSizeHiPx = js.getHeight();
             int i = 0;
             while (i < js.getHeight() && ui.valueForYPosition(i) == hiValue)
             {
                 this.trackSizeLoPx = i++;
             }
             i = js.getHeight();
             while (i >= 0 && ui.valueForYPosition(i) == loValue)
             {
                 this.trackSizeHiPx = i--;
             }
         }
 
         // Adjust based on the number of values between minimum and maximum
         int nr = getIndexMaximum() - getIndexMinimum();
         int pxPerNr = (this.trackSizeHiPx - this.trackSizeLoPx) / nr;
         this.trackSizeLoPx = isHorizontal() ? this.trackSizeLoPx - pxPerNr / 2 : this.trackSizeLoPx + pxPerNr / 2;
         this.trackSizeHiPx = isHorizontal() ? this.trackSizeHiPx + pxPerNr / 2 : this.trackSizeHiPx - pxPerNr / 2;
     }
 
     /**
      * Calculate the track size (width for a horizontal slider; height for a vertical slider).
      * @return the track size (width for a horizontal slider; height for a vertical slider
      */
     protected int trackSize()
     {
         // recalculate the track size of the previous calculation was carried out before 'pack' or 'setSize'.
         if (this.trackSizeHiPx - this.trackSizeLoPx < 2)
         {
             calculateTrackSize();
         }
         return this.trackSizeHiPx - this.trackSizeLoPx;
     }
 
     /**
      * Calculate x pixel (horizontal) or y pixel (vertical) of thumb[i], relative to the panel of the JSlider.
      * @param i the slider number
      * @return the x pixel (horizontal) or y pixel (vertical) of thumb[i], relative to the panel of the JSlider
      */
     protected int thumbPositionPx(final int i)
     {
         JSlider slider = getSlider(i);
         int value = slider.getValue();
         int min = slider.getMinimum();
         int max = slider.getMaximum();
         int ts = trackSize();
         if (getInverted())
         {
             return this.trackSizeLoPx + (int) (1.0 * ts * (max - value) / (max - min));
         }
         return this.trackSizeLoPx + (int) (1.0 * ts * (value - min) / (max - min));
     }
 
     /**
      * Return the glass pane on top of the multislider.
      * @return the glass pane on top of the multislider
      */
     protected DispatcherPane getDispatcherPane()
     {
         return this.dispatcherPane;
     }
 
     /**
      * Gets the UI object which implements the L&amp;F for this component.
      * @return the SliderUI object that implements the Slider L&amp;F
      */
     @Override
     public SliderUI getUI()
     {
         return this.sliders[0].getUI();
     }
 
     /**
      * Sets the UI object which implements the L&amp;F for all underlying sliders.
      * @param ui the SliderUI L&amp;F object
      */
     public void setUI(final SliderUI ui)
     {
         for (var slider : this.sliders)
         {
             try
             {
                 slider.setUI(ui.getClass().getDeclaredConstructor().newInstance());
             }
             catch (Exception exception)
             {
                 // silently fail
             }
         }
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Resets the UI property to a value from the current look and feel for all underlying sliders.
      */
     @Override
     public void updateUI()
     {
         for (var slider : this.sliders)
         {
             slider.updateUI();
         }
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Returns the name of the L&amp;F class that renders this component.
      * @return the string "SliderUI"
      */
     @Override
     public String getUIClassID()
     {
         return this.sliders[0].getUIClassID();
     }
 
     /**
      * Adds a ChangeListener to the multislider.
      * @param listener the ChangeListener to add
      */
     public void addChangeListener(final ChangeListener listener)
     {
         this.listenerList.add(ChangeListener.class, listener);
     }
 
     /**
      * Removes a ChangeListener from the multislider.
      * @param listener the ChangeListener to remove
      */
     public void removeChangeListener(final ChangeListener listener)
     {
         this.listenerList.remove(ChangeListener.class, listener);
     }
 
     /**
      * Returns an array of all the <code>ChangeListener</code>s added to this MultiSlider with addChangeListener().
      * @return all of the <code>ChangeListener</code>s added or an empty array if no listeners have been added
      */
     public ChangeListener[] getChangeListeners()
     {
         return this.listenerList.getListeners(ChangeListener.class);
     }
 
     /**
      * Send a {@code ChangeEvent}, whose source is this {@code MultiSlider}, to all {@code ChangeListener}s that have registered
      * interest in {@code ChangeEvent}s. This method is called each time a {@code ChangeEvent} is received from the model of one
      * of the underlying sliders.
      * <p>
      * The event instance is created if necessary, and stored in {@code changeEvent}.
      * </p>
      */
     protected void fireStateChanged()
     {
         // See if an actual state change has occurred
         boolean changed = false;
         for (int i = 0; i < getNumberOfThumbs(); i++)
         {
             if (this.lastIndexValues[i] != this.sliders[i].getValue())
             {
                 changed = true;
                 this.lastIndexValues[i] = this.sliders[i].getValue();
             }
         }
 
         if (changed)
         {
             // Note that the listener array has the classes at the even places, and the listeners at the odd places (yuck).
             Object[] listeners = this.listenerList.getListenerList();
             for (int i = listeners.length - 2; i >= 0; i -= 2)
             {
                 if (listeners[i] == ChangeListener.class)
                 {
                     if (this.changeEvent == null)
                     {
                         this.changeEvent = new ChangeEvent(this);
                     }
                     ((ChangeListener) listeners[i + 1]).stateChanged(this.changeEvent);
                 }
             }
         }
     }
 
     /**
      * Adds a FinalValueChangeListener to the multislider.
      * @param listener the FinalValueChangeListener to add
      */
     public void addFinalValueChangeListener(final FinalValueChangeListener listener)
     {
         this.listenerList.add(FinalValueChangeListener.class, listener);
     }
 
     /**
      * Removes a FinalValueChangeListener from the multislider.
      * @param listener the FinalValueChangeListener to remove
      */
     public void removeFinalValueChangeListener(final FinalValueChangeListener listener)
     {
         this.listenerList.remove(FinalValueChangeListener.class, listener);
     }
 
     /**
      * Returns an array of all the <code>FinalValueChangeListener</code>s added to this MultiSlider with
      * addFinalValueChangeListener().
      * @return all of the <code>FinalValueChangeListener</code>s added or an empty array if no listeners have been added
      */
     public FinalValueChangeListener[] getFinalValueChangeListeners()
     {
         return this.listenerList.getListeners(FinalValueChangeListener.class);
     }
 
     /**
      * Send a {@code ChangeEvent}, whose source is this {@code MultiSlider}, to all {@code FinalValueChangeListener}s that have
      * registered interest in {@code ChangeEvent}s. This method is called when a change is final, e.g., after setValue(...),
      * setInitialValues(), mouse up, and leaving the slider window after a drag event. Note that the {@code ChangeEvent}s are
      * NOT fired when a value of an underlying slider is changed directly. The regular ChangeListener does fire these changes.
      * <p>
      * The event instance is created if necessary, and stored in {@code changeEvent}.
      * </p>
      */
     protected void fireFinalValueChanged()
     {
         // Note that the listener array has the classes at the even places, and the listeners at the odd places (yuck).
         Object[] listeners = this.listenerList.getListenerList();
         for (int i = listeners.length - 2; i >= 0; i -= 2)
         {
             if (listeners[i] == FinalValueChangeListener.class)
             {
                 if (this.changeEvent == null)
                 {
                     this.changeEvent = new ChangeEvent(this);
                 }
                 ((FinalValueChangeListener) listeners[i + 1]).stateChanged(this.changeEvent);
             }
         }
     }
 
     /**
      * Translate an index to a value.
      * @param index the index on the slider scale to convert
      * @return the corresponding value
      */
     protected abstract T mapIndexToValue(int index);
 
     /**
      * Translate a value to an index.
      * @param value the value to convert to an index
      * @return the corresponding index
      * @throws IllegalArgumentException when value cannot be mapped onto an index
      */
     protected abstract int mapValueToIndex(T value);
 
     /**
      * Returns the slider's current value for slider[i].
      * @param i the thumb to retrieve the value from
      * @return the current value of slider[i]
      * @throws IllegalArgumentException when no value is present for the index
      */
     public T getValue(final int i)
     {
         return mapIndexToValue(getIndexValue(i));
     }
 
     /**
      * Sets the slider's current value to {@code value}. This method forwards the new value to the model. If the new value is
      * different from the previous value, all change listeners are notified.
      * @param i the thumb to set the value for
      * @param value the new value
      */
     public void setValue(final int i, final T value)
     {
         int n = mapValueToIndex(value);
         setIndexValue(i, n);
     }
 
     /**
      * Returns the slider's current index value for slider[i] from the {@code BoundedRangeModel}.
      * @param i the thumb to retrieve the value from
      * @return the current index value of slider[i]
      */
     public int getIndexValue(final int i)
     {
         return this.sliders[i].getModel().getValue();
     }
 
     /**
      * Sets the slider's current index value to {@code n}. This method forwards the new value to the model.
      * <p>
      * The data model (an instance of {@code BoundedRangeModel}) handles any mathematical issues arising from assigning faulty
      * values. See the {@code BoundedRangeModel} documentation for details.
      * </p>
      * If the new value is different from the previous value, all change listeners are notified.
      * @param i the thumb to set the value for
      * @param n the new index value
      */
     protected void setIndexValue(final int i, final int n)
     {
         Throw.when(n < getIndexMinimum() || n > getIndexMaximum(), IllegalArgumentException.class,
                 "setValue(%d) not in range [%d, %d]", n, getIndexMinimum(), getIndexMaximum());
         this.sliders[i].setValue(n);
         checkRestrictions(i);
         this.sliders[i].invalidate();
         this.sliders[i].repaint();
         fireFinalValueChanged();
     }
 
     /**
      * Returns the minimum value supported by the slider from the <code>BoundedRangeModel</code>.
      * @return the value of the model's minimum property
      */
     protected int getIndexMinimum()
     {
         return this.sliders[0].getMinimum();
     }
 
     /**
      * Sets the slider's minimum value to {@code minimum}. This method forwards the new minimum value to the models of all
      * underlying sliders.
      * <p>
      * The data model (an instance of {@code BoundedRangeModel}) handles any mathematical issues arising from assigning faulty
      * values. See the {@code BoundedRangeModel} documentation for details.
      * </p>
      * If the new minimum value is different from the previous minimum value, all change listeners are notified.
      * @param minimum the new minimum
      */
     protected void setIndexMinimum(final int minimum)
     {
         Throw.when(minimum >= getIndexMaximum(), IllegalArgumentException.class, "setMinimum(%d) >= maximum %d", minimum,
                 getIndexMaximum());
         int oldMin = getIndexMinimum();
         for (var slider : this.sliders)
         {
             slider.setMinimum(minimum);
         }
         checkRestrictions();
         for (var slider : this.sliders)
         {
             slider.invalidate();
         }
         invalidate();
         fireFinalValueChanged();
         firePropertyChange("minimum", Integer.valueOf(oldMin), Integer.valueOf(minimum));
         calculateTrackSize();
     }
 
     /**
      * Return the minimum value supported by the multislider.
      * @return the minimum typed value of the multislider
      */
     public T getMinimum()
     {
         return mapIndexToValue(getIndexMinimum());
     }
 
     /**
      * Set the minimum value supported by the multislider.
      * @param minimum the new minimum typed value of the multislider
      */
     public void setMinimum(final T minimum)
     {
         setIndexMinimum(mapValueToIndex(minimum));
     }
 
     /**
      * Returns the maximum value supported by the slider from the <code>BoundedRangeModel</code>.
      * @return the value of the model's maximum property
      */
     protected int getIndexMaximum()
     {
         return this.sliders[0].getMaximum();
     }
 
     /**
      * Sets the slider's maximum value to {@code maximum}. This method forwards the new maximum value to the models of all
      * underlying sliders.
      * <p>
      * The data model (an instance of {@code BoundedRangeModel}) handles any mathematical issues arising from assigning faulty
      * values. See the {@code BoundedRangeModel} documentation for details.
      * </p>
      * If the new maximum value is different from the previous maximum value, all change listeners are notified.
      * @param maximum the new maximum
      */
     protected void setIndexMaximum(final int maximum)
     {
         Throw.when(maximum <= getIndexMinimum(), IllegalArgumentException.class, "setMaximum(%d) >= minimum %d", maximum,
                 getIndexMinimum());
         int oldMax = getIndexMaximum();
         for (var slider : this.sliders)
         {
             slider.setMaximum(maximum);
         }
         checkRestrictions();
         for (var slider : this.sliders)
         {
             slider.invalidate();
         }
         fireFinalValueChanged();
         firePropertyChange("maximum", Integer.valueOf(oldMax), Integer.valueOf(maximum));
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Return the maximum value supported by the multislider.
      * @return the maximum typed value of the multislider
      */
     public T getMaximum()
     {
         return mapIndexToValue(getIndexMaximum());
     }
 
     /**
      * Set the maximum value supported by the multislider.
      * @param maximum the new maximum typed value of the multislider
      */
     public void setMaximum(final T maximum)
     {
         setIndexMaximum(mapValueToIndex(maximum));
     }
 
     /**
      * Returns the "extent" from the <code>BoundedRangeModel</code>. This represents the range of values "covered" by the thumb.
      * @return an int representing the extent
      */
     public int getExtent()
     {
         return this.sliders[0].getExtent();
     }
 
     /**
      * Sets the size of the range "covered" by the thumb for all underlying slider objects. Most look and feel implementations
      * will change the value by this amount if the user clicks on either side of the thumb. This method just forwards the new
      * extent value to the model.
      * <p>
      * The data model (an instance of {@code BoundedRangeModel}) handles any mathematical issues arising from assigning faulty
      * values. See the {@code BoundedRangeModel} documentation for details.
      * </p>
      * If the new extent value is different from the previous extent value, all change listeners are notified.
      * @param extent the new extent
      */
     public void setExtent(final int extent)
     {
         for (var slider : this.sliders)
         {
             slider.setExtent(extent);
         }
     }
 
     /**
      * Return this multislider's vertical or horizontal orientation.
      * @return {@code SwingConstants.VERTICAL} or {@code SwingConstants.HORIZONTAL}
      */
     public int getOrientation()
     {
         return this.sliders[0].getOrientation();
     }
 
     /**
      * Return whether the orientation of the multislider is horizontal or not.
      * @return true if the orientation of the multislider is horizontal, false when not.
      */
     public boolean isHorizontal()
     {
         return getOrientation() == SwingConstants.HORIZONTAL;
     }
 
     /**
      * Return whether the orientation of the multislider is vertical or not.
      * @return true if the orientation of the multislider is vertical , false when not.
      */
     public boolean isVertical()
     {
         return !isHorizontal();
     }
 
     /**
      * Set the slider's orientation to either {@code SwingConstants.VERTICAL} or {@code SwingConstants.HORIZONTAL}.
      * @param orientation {@code HORIZONTAL} or {@code VERTICAL}
      * @throws IllegalArgumentException if orientation is not one of {@code VERTICAL}, {@code HORIZONTAL}
      */
     public void setOrientation(final int orientation)
     {
         for (var slider : this.sliders)
         {
             slider.setOrientation(orientation);
             slider.invalidate();
         }
         this.dispatcherPane.setPreferredSize(new Dimension(this.sliders[0].getSize()));
         invalidate();
         calculateTrackSize();
     }
 
     @Override
     public void setFont(final Font font)
     {
         for (var slider : this.sliders)
         {
             slider.setFont(font);
             slider.invalidate();
         }
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Returns the dictionary of what labels to draw at which values.
      * @return the <code>Dictionary</code> containing labels and where to draw them
      */
     @SuppressWarnings("rawtypes")
     public Dictionary getLabelTable()
     {
         return this.sliders[0].getLabelTable();
     }
 
     /**
      * Specify what label will be drawn at any given value. The key-value pairs are of this format:
      * <code>{ Integer value, java.swing.JComponent label }</code>. An easy way to generate a standard table of value labels is
      * by using the {@code createStandardLabels} method.
      * @param labels new {@code Dictionary} of labels, or {@code null} to remove all labels
      */
     @SuppressWarnings("rawtypes")
     public void setLabelTable(final Dictionary labels)
     {
         for (var slider : this.sliders)
         {
             slider.setLabelTable(labels);
             slider.invalidate();
         }
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Creates a {@code Hashtable} of numerical text labels, starting at the slider minimum, and using the increment specified.
      * For example, if you call <code>createStandardLabels( 10 )</code> and the slider minimum is zero, then labels will be
      * created for the values 0, 10, 20, 30, and so on.
      * <p>
      * For the labels to be drawn on the slider, the returned {@code Hashtable} must be passed into {@code setLabelTable}, and
      * {@code setPaintLabels} must be set to {@code true}.
      * <p>
      * For further details on the makeup of the returned {@code Hashtable}, see the {@code setLabelTable} documentation.
      * @param increment distance between labels in the generated hashtable
      * @return a new {@code Hashtable} of labels
      * @throws IllegalArgumentException if {@code increment} is less than or equal to zero
      */
     public Hashtable<Integer, JComponent> createStandardLabels(final int increment)
     {
         return createStandardLabels(increment, getIndexMinimum());
     }
 
     /**
      * Creates a {@code Hashtable} of text labels, starting at the starting point specified, and using the increment specified.
      * For example, if you call <code>createStandardLabels( 10, 2 )</code>, then labels will be created for the index values 2,
      * 12, 22, 32, and so on.
      * <p>
      * For the labels to be drawn on the slider, the returned {@code Hashtable} must be passed into {@code setLabelTable}, and
      * {@code setPaintLabels} must be set to {@code true}.
      * <p>
      * For further details on the makeup of the returned {@code Hashtable}, see the {@code setLabelTable} documentation.
      * @param increment distance between labels in the generated hashtable
      * @param startIndex value at which the labels will begin
      * @return a new {@code Hashtable} of labels
      * @exception IllegalArgumentException if {@code start} is out of range, or if {@code increment} is less than or equal to
      *                zero
      */
     public Hashtable<Integer, JComponent> createStandardLabels(final int increment, final int startIndex)
     {
         Throw.when(increment <= 0, IllegalArgumentException.class, "increment should be > 0");
         Throw.when(startIndex < getIndexMinimum() || startIndex > getIndexMaximum(), IllegalArgumentException.class,
                 "startIndex should be between minimum index and maximum index");
         Hashtable<Integer, JComponent> labels = new Hashtable<>();
         for (int i = startIndex; i <= getIndexMaximum(); i += increment)
         {
             labels.put(i, new JLabel(format(mapIndexToValue(i))));
         }
         return labels;
     }
 
     /**
      * Format a value for e.g., the labels of the slider. By default, the formatting is done with {@code toString()}, but this
      * can be overridden.
      * @param value the value to format
      * @return a formatted string representation of the value
      */
     protected String format(final T value)
     {
         return value.toString();
     }
 
     /**
      * Returns true if the value-range shown for the slider is reversed.
      * @return true if the slider values are reversed from their normal order
      */
     public boolean getInverted()
     {
         return this.sliders[0].getInverted();
     }
 
     /**
      * Specify true to reverse the value-range shown for the slider and false to put the value range in the normal order. The
      * order depends on the slider's <code>ComponentOrientation</code> property. Normal (non-inverted) horizontal sliders with a
      * <code>ComponentOrientation</code> value of <code>LEFT_TO_RIGHT</code> have their maximum on the right. Normal horizontal
      * sliders with a <code>ComponentOrientation</code> value of <code>RIGHT_TO_LEFT</code> have their maximum on the left.
      * Normal vertical sliders have their maximum on the top. These labels are reversed when the slider is inverted.
      * <p>
      * By default, the value of this property is {@code false}.
      * @param b true to reverse the slider values from their normal order
      */
     public void setInverted(final boolean b)
     {
         for (var slider : this.sliders)
         {
             slider.setInverted(b);
             slider.invalidate();
         }
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * This method returns the major tick spacing. The number that is returned represents the distance, measured in values,
      * between each major tick mark. If you have a slider with a range from 0 to 50 and the major tick spacing is set to 10, you
      * will get major ticks next to the following values: 0, 10, 20, 30, 40, 50.
      * @return the number of values between major ticks
      */
     public int getMajorTickSpacing()
     {
         return this.sliders[0].getMajorTickSpacing();
     }
 
     /**
      * This method sets the major tick spacing. The number that is passed in represents the distance, measured in values,
      * between each major tick mark. If you have a slider with a range from 0 to 50 and the major tick spacing is set to 10, you
      * will get major ticks next to the following values: 0, 10, 20, 30, 40, 50.
      * <p>
      * In order for major ticks to be painted, {@code setPaintTicks} must be set to {@code true}.
      * </p>
      * This method will also set up a label table for you. If there is not already a label table, and the major tick spacing is
      * {@code > 0}, and {@code getPaintLabels} returns {@code true}, a standard label table will be generated (by calling
      * {@code createStandardLabels}) with labels at the major tick marks. For the example above, you would get text labels: "0",
      * "10", "20", "30", "40", "50". The label table is then set on the slider by calling {@code setLabelTable}.
      * @param n new value for the {@code majorTickSpacing} property
      */
     public void setMajorTickSpacing(final int n)
     {
         int oldValue = getMajorTickSpacing();
         for (var slider : this.sliders)
         {
             slider.setMajorTickSpacing(n);
             slider.invalidate();
         }
         firePropertyChange("majorTickSpacing", oldValue, n);
         invalidate();
     }
 
     /**
      * This method returns the minor tick spacing. The number that is returned represents the distance, measured in values,
      * between each minor tick mark. If you have a slider with a range from 0 to 50 and the minor tick spacing is set to 10, you
      * will get minor ticks next to the following values: 0, 10, 20, 30, 40, 50.
      * @return the number of values between minor ticks
      */
     public int getMinorTickSpacing()
     {
         return this.sliders[0].getMinorTickSpacing();
     }
 
     /**
      * This method sets the minor tick spacing. The number that is passed in represents the distance, measured in values,
      * between each minor tick mark. If you have a slider with a range from 0 to 50 and the minor tick spacing is set to 10, you
      * will get minor ticks next to the following values: 0, 10, 20, 30, 40, 50.
      * <p>
      * In order for minor ticks to be painted, {@code setPaintTicks} must be set to {@code true}.
      * @param n new value for the {@code minorTickSpacing} property
      * @see #getMinorTickSpacing
      * @see #setPaintTicks
      */
     public void setMinorTickSpacing(final int n)
     {
         int oldValue = getMinorTickSpacing();
         for (var slider : this.sliders)
         {
             slider.setMinorTickSpacing(n);
             slider.invalidate();
         }
         firePropertyChange("minorTickSpacing", oldValue, n);
         invalidate();
     }
 
     /**
      * Returns true if the thumb (and the data value it represents) resolve to the closest tick mark next to where the user
      * positioned the thumb.
      * @return true if the value snaps to the nearest tick mark, else false
      */
     public boolean getSnapToTicks()
     {
         return this.sliders[0].getSnapToTicks();
     }
 
     /**
      * Specifying true makes the thumb (and the data value it represents) resolve to the closest tick mark next to where the
      * user positioned the thumb. By default, this property is {@code false}.
      * @param b true to snap the thumb to the nearest tick mark
      */
     public void setSnapToTicks(final boolean b)
     {
         boolean oldValue = getSnapToTicks();
         for (var slider : this.sliders)
         {
             slider.setSnapToTicks(b);
         }
         firePropertyChange("snapToTicks", oldValue, b);
     }
 
     /**
      * Tells if tick marks are to be painted.
      * @return true if tick marks are painted, else false
      */
     public boolean getPaintTicks()
     {
         return this.sliders[0].getPaintTicks();
     }
 
     /**
      * Determines whether tick marks are painted on the slider. By default, this property is {@code false}.
      * @param b whether or not tick marks should be painted
      */
     public void setPaintTicks(final boolean b)
     {
         boolean oldValue = getPaintTicks();
         for (var slider : this.sliders)
         {
             slider.setPaintTicks(b);
             slider.invalidate();
         }
         firePropertyChange("paintTicks", oldValue, b);
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Tells if the track (area the slider slides in) is to be painted.
      * @return true if track is painted, else false
      */
     public boolean getPaintTrack()
     {
         return this.sliders[0].getPaintTrack();
     }
 
     /**
      * Determines whether the track is painted on the slider. By default, this property is {@code true}. It is up to the look
      * and feel to honor this property, some may choose to ignore it.
      * @param b whether or not to paint the slider track
      * @see #getPaintTrack
      */
     public void setPaintTrack(final boolean b)
     {
         boolean oldValue = getPaintTrack();
         this.sliders[0].setPaintTrack(b);
         firePropertyChange("paintTrack", oldValue, b);
         calculateTrackSize();
     }
 
     /**
      * Tells if labels are to be painted.
      * @return true if labels are painted, else false
      */
     public boolean getPaintLabels()
     {
         return this.sliders[0].getPaintLabels();
     }
 
     /**
      * Determines whether labels are painted on the slider.
      * <p>
      * This method will also set up a label table for you. If there is not already a label table, and the major tick spacing is
      * {@code > 0}, a standard label table will be generated (by calling {@code createStandardLabels}) with labels at the major
      * tick marks. The label table is then set on the slider by calling {@code setLabelTable}.
      * </p>
      * By default, this property is {@code false}.
      * @param b whether or not to paint labels
      */
     public void setPaintLabels(final boolean b)
     {
         boolean oldValue = getPaintLabels();
         for (var slider : this.sliders)
         {
             slider.setPaintLabels(b);
             slider.invalidate();
         }
         firePropertyChange("paintLabels", oldValue, b);
         invalidate();
         calculateTrackSize();
     }
 
     /**
      * Set whether passing of the thumbs is allowed, and check whether thumb values are in line with restrictions.
      * @param b whether passing of the thumbs is allowed or not
      */
     public void setPassing(final boolean b)
     {
         this.passing = b;
         if (!this.passing)
         {
             checkRestrictions();
         }
     }
 
     /**
      * Return whether passing of the thumbs is allowed.
      * @return whether passing of the thumbs is allowed or not
      */
     public boolean getPassing()
     {
         return this.passing;
     }
 
     /**
      * Set whether overlap of the thumbs is allowed, and check whether thumb values are in line with restrictions.
      * @param b whether overlap of the thumbs is allowed or not
      */
     public void setOverlap(final boolean b)
     {
         this.overlap = b;
         if (!this.overlap)
         {
             checkRestrictions();
         }
     }
 
     /**
      * Return whether overlap of the thumbs is allowed.
      * @return whether overlap of the thumbs is allowed or not
      */
     public boolean getOverlap()
     {
         return this.overlap;
     }
 
     /**
      * Check restrictions on all thumb values and correct values where necessary.
      * @return whether compliance with the restrictions is ok; false means violation
      */
     protected boolean checkRestrictions()
     {
         boolean ret = true;
         if (!getPassing())
         {
             for (int i = 1; i < getNumberOfThumbs(); i++)
             {
                 // see if we need to push values 'up'
                 if (getIndexValue(i) <= getIndexValue(i - 1))
                 {
                     getSlider(i).setValue(getIndexValue(i - 1));
                     ret = false;
                 }
             }
             for (int i = getNumberOfThumbs() - 1; i >= 1; i--)
             {
                 // see if we need to push values 'down'
                 if (getIndexValue(i) <= getIndexValue(i - 1))
                 {
                     getSlider(i - 1).setValue(getIndexValue(i));
                     ret = false;
                 }
             }
         }
         if (!getOverlap())
         {
             for (int i = 1; i < getNumberOfThumbs(); i++)
             {
                 // see if we need to push values 'up'
                 if (getIndexValue(i) <= getIndexValue(i - 1))
                 {
                     getSlider(i).setValue(getIndexValue(i - 1) + 1);
                     ret = false;
                 }
             }
             for (int i = getNumberOfThumbs() - 1; i >= 1; i--)
             {
                 // see if we need to push values 'down'
                 if (getIndexValue(i) <= getIndexValue(i - 1))
                 {
                     getSlider(i - 1).setValue(getIndexValue(i) - 1);
                     ret = false;
                 }
             }
         }
         if (!ret)
         {
             invalidate();
             repaint();
         }
         return ret;
     }
 
     /**
      * Check restrictions on the thumb values of thumb 'index' and correct values where necessary.
      * @param index the slider for which to check (the only one whose value should change)
      * @return whether compliance with the restrictions is ok; false means violation
      */
     protected boolean checkRestrictions(final int index)
     {
         boolean ret = true;
         if (!getPassing())
         {
             if (index > 0 && getIndexValue(index) <= getIndexValue(index - 1))
             {
                 getSlider(index).setValue(getIndexValue(index - 1));
                 ret = false;
             }
             if (index < getNumberOfThumbs() - 1 && getIndexValue(index) >= getIndexValue(index + 1))
             {
                 getSlider(index).setValue(getIndexValue(index + 1));
                 ret = false;
             }
         }
         if (!getOverlap())
         {
             if (index > 0 && getIndexValue(index) <= getIndexValue(index - 1))
             {
                 getSlider(index).setValue(getIndexValue(index - 1) + 1);
                 ret = false;
             }
             if (index < getNumberOfThumbs() - 1 && getIndexValue(index) >= getIndexValue(index + 1))
             {
                 getSlider(index).setValue(getIndexValue(index + 1) - 1);
                 ret = false;
             }
         }
         if (!ret)
         {
             getSlider(index).invalidate();
             getSlider(index).repaint();
         }
         return ret;
     }
 
     /**
      * The DispatcherPane class, which is a glass pane sitting on top of the sliders to dispatch the mouse event to the correct
      * slider class. Note that the mouse coordinates are relative to the component itself, so a translation might be needed. The
      * <code>SwingUtilities.convertPoint()</code> method can make the conversion.
      */
     protected static class DispatcherPane extends JComponent
     {
         /** */
         private static final long serialVersionUID = 1L;
 
         /** the pointer to the multislider object; protected to access it by the mouse handlers. */
         @SuppressWarnings("checkstyle:visibilitymodifier")
         protected final AbstractMultiSlider<?> multiSlider;
 
         /**
          * Return the closest slider number based on x (horizontal) or y (vertical) locations of the thumbs. When two or more
          * thumbs are at the exact same distance (e.g., because they overlap), the first slider found that has a movement option
          * in the direction of the mouse will be returned.
          * @param p the point (e.g., of a mouse position)
          * @return the index(es) of the closest slider(s)
          */
         int closestSliderIndex(final Point p)
         {
             if (this.multiSlider.getBusySlider() >= 0)
             {
                 return this.multiSlider.getBusySlider();
             }
 
             int mindist = Integer.MAX_VALUE; // non-absolute lowest distance of (mouse) position in pixels
             int minIndex = -1; // int scale value of thumb at closest position
             int mini = -1; // thumb index of closest position
             int loi = Integer.MAX_VALUE; // lowest thumb number on closest position
             int hii = -1; // highest thumb number on closest position
             for (int i = 0; i < this.multiSlider.getNumberOfThumbs(); i++)
             {
                 int posPx = this.multiSlider.thumbPositionPx(i);
                 int dist = this.multiSlider.isHorizontal() ? posPx - p.x : posPx - (getHeight() - p.y);
                 if (Math.abs(dist) == Math.abs(mindist))
                 {
                     hii = i;
                 }
                 else if (Math.abs(dist) < Math.abs(mindist))
                 {
                     mindist = dist;
                     mini = i;
                     minIndex = this.multiSlider.getIndexValue(i);
                     loi = i;
                     hii = i;
                 }
             }
 
             // if only one closest slider (loi == hii), or no passing restrictions: move any slider!
             if (loi == hii || this.multiSlider.getPassing())
             {
                 return mini;
             }
             if (minIndex == this.multiSlider.getIndexMinimum()) // hi movement only
             {
                 return hii;
             }
             if (minIndex == this.multiSlider.getIndexMaximum()) // lo movement only
             {
                 return loi;
             }
             if (mindist > 0) // mouse to the left
             {
                 return loi;
             }
             return hii; // mouse to the right
         }
 
         /**
          * @param e the MouseEvent to dispatch to the sliders.
          * @param always indicates whether we always need to send the event
          * @return the slider index to which the event was dispatched; -1 if none
          */
         int dispatch(final MouseEvent e, final boolean always)
         {
             var slider = DispatcherPane.this.multiSlider.getSlider(0);
             Point pSlider = SwingUtilities.convertPoint(DispatcherPane.this, e.getPoint(), slider);
             if (always || (pSlider.x >= 0 && pSlider.x <= slider.getSize().width && pSlider.y >= 0
                     && pSlider.y <= slider.getSize().height))
             {
                 int index = closestSliderIndex(pSlider);
                 MouseEvent meSlider = new MouseEvent((Component) e.getSource(), e.getID(), e.getWhen(), e.getModifiersEx(),
                         pSlider.x, pSlider.y, e.getClickCount(), e.isPopupTrigger(), e.getButton());
                 try
                 {
                     DispatcherPane.this.multiSlider.getSlider(index).dispatchEvent(meSlider);
                 }
                 catch (Exception exception)
                 {
                     exception.printStackTrace();
                     System.out.println("error dispatching mouseEvent " + meSlider);
                 }
                 setBusySlider(index);
                 return index;
             }
             return -1;
         }
 
         /**
          * Reset the busy slider -- action over. Call this method BEFORE processing the MouseEvent. In that way, the
          * ChangeListener will fire a StateChange while the busy slider is -1 -- indicating that there is a final value.
          * @param index the slider number that is busy, or -1 if none
          */
         void setBusySlider(final int index)
         {
             this.multiSlider.setBusySlider(index);
         }
 
         /**
          * Indicate whether the multislider is busy with handling an action (e.g., drag, mouse down). Note that the busy flag
          * has to be set BEFORE the mouse event is handled, to allow a listener to the ChangeEvent to only react when an action
          * is completed.
          * @param b whether the multislider is busy with handling an action or not
          */
         void setBusy(final boolean b)
         {
             this.multiSlider.setBusy(b);
         }
 
         /**
          * Check whether minimum, maximum, passing or overlap restrictions were violated, and if so, adjust.
          * @param index the slider number for which to check
          */
         void checkRestrictions(final int index)
         {
             this.multiSlider.checkRestrictions(index);
         }
 
         /**
          * Create a glass pane on top of the sliders.
          * @param multiSlider the multislider for which this is the glass pane
          */
         public DispatcherPane(final AbstractMultiSlider<?> multiSlider)
         {
             this.multiSlider = multiSlider;
             setOpaque(false);
 
             addMouseListener(new MouseListener()
             {
                 @Override
                 public void mouseReleased(final MouseEvent e)
                 {
                     setBusy(false);
                     int index = dispatch(e, false);
                     if (index >= 0)
                     {
                         checkRestrictions(index);
                         DispatcherPane.this.multiSlider.fireFinalValueChanged();
                     }
                     setBusySlider(-1);
                 }
 
                 @Override
                 public void mousePressed(final MouseEvent e)
                 {
                     setBusy(true);
                     int index = dispatch(e, false);
                     setBusySlider(index);
                     if (index < 0)
                     {
                         setBusy(false);
                     }
                 }
 
                 @Override
                 public void mouseExited(final MouseEvent e)
                 {
                     setBusy(false);
                     // emulate a mouse release somewhere on the current slider to force correct update
                     var ms = DispatcherPane.this.multiSlider;
                     if (ms.getBusySlider() >= 0)
                     {
                         JSlider js = ms.getSlider(ms.getBusySlider());
                         checkRestrictions(ms.getBusySlider());
                         MouseEvent meSlider = new MouseEvent(js, MouseEvent.MOUSE_RELEASED, e.getWhen(), 0, 10, 10, 1, false,
                                 MouseEvent.BUTTON1);
                         js.dispatchEvent(meSlider);
                         ms.fireFinalValueChanged();
                     }
                     setBusySlider(-1);
                 }
 
                 @Override
                 public void mouseEntered(final MouseEvent e)
                 {
                     // no action
                 }
 
                 @Override
                 public void mouseClicked(final MouseEvent e)
                 {
                     // completely caught by pressed + released (or pressed + dragged + released)
                 }
             });
 
             addMouseMotionListener(new MouseMotionAdapter()
             {
                 @Override
                 public void mouseDragged(final MouseEvent e)
                 {
                     setBusy(true);
                     int index = dispatch(e, false);
                     setBusySlider(index);
                     if (index < 0)
                     {
                         setBusy(false);
                     }
                     else
                     {
                         checkRestrictions(index);
                     }
                 }
 
                 @Override
                 public void mouseMoved(final MouseEvent e)
                 {
                     // Note: possibly we can trigger an 'mouse entered' when the mouse enters the slider pane,
                     // and a 'mouse exited' when the mouse exits the slider pane.
                 }
             });
         }
     }
 
     /**
      * The LabelPanel is draw above a horizontal slider or left of a vertical slider and displays labels for the thumbs of the
      * slider, so one can see which one is which.
      */
     protected static class LabelPanel extends JPanel
     {
         /** */
         private static final long serialVersionUID = 1L;
 
         /** a pointer to the multislider. */
         private final AbstractMultiSlider<?> multiSlider;
 
         /**
          * Default constructor.
          * @param multiSlider the multislider for which this is the LabelPanel.
          */
         public LabelPanel(final AbstractMultiSlider<?> multiSlider)
         {
             this.multiSlider = multiSlider;
             repaint();
             this.multiSlider.addChangeListener(new ChangeListener()
             {
                 @Override
                 public void stateChanged(final ChangeEvent e)
                 {
                     repaint();
                 }
             });
         }
 
         @Override
         public void paintComponent(final Graphics g)
         {
             super.paintComponent(g);
             if (LabelPanel.this.multiSlider.isDrawThumbLabels())
             {
                 for (int i = 0; i < this.multiSlider.getNumberOfThumbs(); i++)
                 {
                     int pos = this.multiSlider.thumbPositionPx(i);
                     String s = this.multiSlider.getThumbLabel(i);
                     int sw = g.getFontMetrics().stringWidth(s);
                     int sh = g.getFontMetrics().getHeight();
                     if (this.multiSlider.isHorizontal())
                     {
                         g.drawString(s, pos - sw / 2, 12);
                     }
                     else
                     {
                         g.drawString(s, getWidth() - sw - 10, getHeight() - pos + sh / 2 - 3);
                     }
                 }
             }
         }
     }
 
     /**
      * The FinalValueChangeListener sends a final value to the listeners after mouse-up, leave focus, setValue(...), and
      * setInitialValues().
      */
     public interface FinalValueChangeListener extends ChangeListener
     {
         // no extra events
     }
 }