bundles/org.eclipse.swt/Eclipse SWT/motif/org/eclipse/swt/widgets/ScrollBar.java

/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;

 
import org.eclipse.swt.internal.motif.*;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.events.*;

/**
 * Instances of this class are selectable user interface
 * objects that represent a range of positive, numeric values. 
 * <p>
 * At any given moment, a given scroll bar will have a 
 * single 'selection' that is considered to be its
 * value, which is constrained to be within the range of
 * values the scroll bar represents (that is, between its
 * <em>minimum</em> and <em>maximum</em> values).
 * </p><p>
 * Typically, scroll bars will be made up of five areas:
 * <ol>
 * <li>an arrow button for decrementing the value</li>
 * <li>a page decrement area for decrementing the value by a larger amount</li>
 * <li>a <em>thumb</em> for modifying the value by mouse dragging</li>
 * <li>a page increment area for incrementing the value by a larger amount</li>
 * <li>an arrow button for incrementing the value</li>
 * </ol>
 * Based on their style, scroll bars are either <code>HORIZONTAL</code>
 * (which have a left facing button for decrementing the value and a
 * right facing button for incrementing it) or <code>VERTICAL</code>
 * (which have an upward facing button for decrementing the value
 * and a downward facing buttons for incrementing it).
 * </p><p>
 * On some platforms, the size of the scroll bar's thumb can be
 * varied relative to the magnitude of the range of values it
 * represents (that is, relative to the difference between its
 * maximum and minimum values). Typically, this is used to
 * indicate some proportional value such as the ratio of the
 * visible area of a document to the total amount of space that
 * it would take to display it. SWT supports setting the thumb
 * size even if the underlying platform does not, but in this
 * case the appearance of the scroll bar will not change.
 * </p><p>
 * Scroll bars are created by specifying either <code>H_SCROLL</code>,
 * <code>V_SCROLL</code> or both when creating a <code>Scrollable</code>.
 * They are accessed from the <code>Scrollable</code> using
 * <code>getHorizontalBar</code> and <code>getVerticalBar</code>.
 * </p><p>
 * Note: Scroll bars are not Controls.  On some platforms, scroll bars
 * that appear as part of some standard controls such as a text or list
 * have no operating system resources and are not children of the control.
 * For this reason, scroll bars are treated specially.  To create a control
 * that looks like a scroll bar but has operating system resources, use
 * <code>Slider</code>. 
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>HORIZONTAL, VERTICAL</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see Slider
 * @see Scrollable
 * @see Scrollable#getHorizontalBar
 * @see Scrollable#getVerticalBar
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public class ScrollBar extends Widget {
	Scrollable parent;
	boolean dragSent = false;
ScrollBar () {
	/* Do Nothing */
}
ScrollBar (Scrollable parent, int style) {
	super (parent, checkStyle (style));
	this.parent = parent;
	createWidget (0);
}
/**
 * Adds the listener to the collection of listeners who will
 * be notified when the user changes the receiver's value, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * When <code>widgetSelected</code> is called, the event object detail field contains one of the following values:
 * <code>SWT.NONE</code> - for the end of a drag.
 * <code>SWT.DRAG</code>.
 * <code>SWT.HOME</code>.
 * <code>SWT.END</code>.
 * <code>SWT.ARROW_DOWN</code>.
 * <code>SWT.ARROW_UP</code>.
 * <code>SWT.PAGE_DOWN</code>.
 * <code>SWT.PAGE_UP</code>.
 * <code>widgetDefaultSelected</code> is not called.
 * </p>
 *
 * @param listener the listener which should be notified when the user changes the receiver's value
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener(SelectionListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener(listener);
	addListener(SWT.Selection,typedListener);
	addListener(SWT.DefaultSelection,typedListener);
}
static int checkStyle (int style) {
	return checkBits (style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0);
}
void createHandle (int index) {
	int [] argList = {
		OS.XmNancestorSensitive, 1,
		OS.XmNborderWidth, (style & SWT.BORDER) != 0 ? 1 : 0,
		OS.XmNorientation, ((style & SWT.H_SCROLL) != 0) ? OS.XmHORIZONTAL : OS.XmVERTICAL,
		OS.XmNtraversalOn, 0,
	};
	int parentHandle = parent.scrolledHandle;
	handle = OS.XmCreateScrollBar (parentHandle, null, argList, argList.length / 2);
	if (handle == 0) error (SWT.ERROR_NO_HANDLES);
}
void destroyHandle () {
	super.destroyWidget ();
}
void destroyWidget () {
	parent.destroyScrollBar (this);
	releaseHandle ();
	//parent.sendEvent (SWT.Resize);
}
/**
 * Returns <code>true</code> if the receiver is enabled, and
 * <code>false</code> otherwise. A disabled control is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @return the receiver's enabled state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * 
 * @see #isEnabled
 */
public boolean getEnabled () {
	checkWidget();
	int [] argList = {OS.XmNsensitive, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1] != 0;
}
/**
 * Returns the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed.
 *
 * @return the increment
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getIncrement () {
	checkWidget();
	int [] argList = {OS.XmNincrement, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns the maximum value which the receiver will allow.
 *
 * @return the maximum
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMaximum () {
	checkWidget();
	int [] argList = {OS.XmNmaximum, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns the minimum value which the receiver will allow.
 *
 * @return the minimum
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMinimum () {
	checkWidget();
	int [] argList = {OS.XmNminimum, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected.
 *
 * @return the page increment
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getPageIncrement () {
	checkWidget();
	int [] argList = {OS.XmNpageIncrement, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns the receiver's parent, which must be a Scrollable.
 *
 * @return the receiver's parent
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public Scrollable getParent () {
	checkWidget();
	return parent;
}
/**
 * Returns the single 'selection' that is the receiver's value.
 *
 * @return the selection
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getSelection () {
	checkWidget();
	int [] argList = {OS.XmNvalue, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns a point describing the receiver's size. The
 * x coordinate of the result is the width of the receiver.
 * The y coordinate of the result is the height of the
 * receiver.
 *
 * @return the receiver's size
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public Point getSize () {
	checkWidget();
	int [] argList = {OS.XmNwidth, 0, OS.XmNheight, 0, OS.XmNborderWidth, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	int borders = argList [5] * 2;
	return new Point (argList [1] + borders, argList [3] + borders);
}
/**
 * Returns the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.
 *
 * @return the thumb value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see ScrollBar
 */
public int getThumb () {
	checkWidget();
	int [] argList = {OS.XmNsliderSize, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	return argList [1];
}
/**
 * Returns <code>true</code> if the receiver is visible, and
 * <code>false</code> otherwise.
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, this method
 * may still indicate that it is considered visible even though
 * it may not actually be showing.
 * </p>
 *
 * @return the receiver's visibility state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public boolean getVisible () {
	checkWidget();
	return OS.XtIsManaged (handle);
}
void hookEvents () {
	int windowProc = display.windowProc;
	OS.XtAddCallback (handle, OS.XmNvalueChangedCallback, windowProc, VALUE_CHANGED_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNdragCallback, windowProc, DRAG_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNtoBottomCallback, windowProc, TO_BOTTOM_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNtoTopCallback, windowProc, TO_TOP_CALLBACK);	
	OS.XtAddCallback (handle, OS.XmNincrementCallback, windowProc, INCREMENT_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNdecrementCallback, windowProc, DECREMENT_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNpageIncrementCallback, windowProc, PAGE_INCREMENT_CALLBACK);
	OS.XtAddCallback (handle, OS.XmNpageDecrementCallback, windowProc, PAGE_DECREMENT_CALLBACK);
	OS.XtAddEventHandler (handle, OS.ButtonPressMask, false, windowProc, BUTTON_PRESS);
}
/**
 * Returns <code>true</code> if the receiver is enabled and all
 * of the receiver's ancestors are enabled, and <code>false</code>
 * otherwise. A disabled control is typically not selectable from the
 * user interface and draws with an inactive or "grayed" look.
 *
 * @return the receiver's enabled state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * 
 * @see #getEnabled
 */
public boolean isEnabled () {
	checkWidget();
	return getEnabled () && parent.isEnabled ();
}
/**
 * Returns <code>true</code> if the receiver is visible and all
 * of the receiver's ancestors are visible and <code>false</code>
 * otherwise.
 *
 * @return the receiver's visibility state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #getVisible
 */
public boolean isVisible () {
	checkWidget();
	return getVisible () && parent.isVisible ();
}
void manageChildren () {
	/*
	* Feature in Motif.  Hiding or showing a scroll bar
	* can cause the widget to automatically resize in
	* the OS.  This behavior is unwanted.  The fix is
	* to force the widget to resize to original size.
	*/
	int scrolledHandle = parent.scrolledHandle;
	int [] argList = {OS.XmNwidth, 0, OS.XmNheight, 0, OS.XmNborderWidth, 0};
	if (scrolledHandle != 0) {
		OS.XtGetValues (scrolledHandle, argList, argList.length / 2);
	}
	OS.XtManageChild (handle);
	/*
	* Feature in Motif.  When XtSetValues() is used to restore the width and
	* height of the widget, the new width and height are sometimes ignored.
	* The fix is to use XtResizeWidget().
	*/
	if (scrolledHandle != 0) {
		OS.XtResizeWidget (scrolledHandle, argList [1], argList [3], argList [5]);
	}
}
void propagateWidget (boolean enabled) {
	propagateHandle (enabled, handle, OS.None);
}
void releaseHandle () {
	super.releaseHandle ();
	parent = null;
}
void releaseParent () {
	super.releaseParent ();
	if (parent.horizontalBar == this) parent.horizontalBar = null;
	if (parent.verticalBar == this) parent.verticalBar = null;
}
/**
 * Removes the listener from the collection of listeners who will
 * be notified when the user changes the receiver's value.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener(SelectionListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook(SWT.Selection, listener);
	eventTable.unhook(SWT.DefaultSelection,listener);	
}
void sendScrollEvent (int detail) {
	Event event = new Event ();
	event.detail = detail;
	sendEvent (SWT.Selection, event);
	/*
	* Feature in Motif.  When a scroll bar is selected,
	* it does not make the shell active.  The fix is to
	* make the shell active.
	*/
	Shell shell = parent.getShell ();
	shell.bringToTop (true);
}
/**
 * Enables the receiver if the argument is <code>true</code>,
 * and disables it otherwise. A disabled control is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @param enabled the new enabled state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setEnabled (boolean enabled) {
	checkWidget();
	int [] argList = {OS.XmNsensitive, enabled ? 1 : 0};
	OS.XtSetValues (handle, argList, argList.length / 2);
}
/**
 * Sets the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed to the argument, which must be at least 
 * one.
 *
 * @param value the new increment (must be greater than zero)
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setIncrement (int value) {
	checkWidget();
	if (value < 1) return;
	int [] argList = {OS.XmNincrement, value};
	OS.XtSetValues (handle, argList, argList.length / 2);
}
/**
 * Sets the maximum. If this value is negative or less than or
 * equal to the minimum, the value is ignored. If necessary, first
 * the thumb and then the selection are adjusted to fit within the
 * new range.
 *
 * @param value the new maximum
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMaximum (int value) {
	checkWidget();
	if (value < 0) return;
	int [] argList = {OS.XmNmaximum, value};
	boolean warnings = display.getWarnings ();
	display.setWarnings (false);
	OS.XtSetValues (handle, argList, argList.length / 2);
	display.setWarnings (warnings);
}
/**
 * Sets the minimum value. If this value is negative or greater
 * than or equal to the maximum, the value is ignored. If necessary,
 * first the thumb and then the selection are adjusted to fit within
 * the new range.
 *
 * @param value the new minimum
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinimum (int value) {
	checkWidget();
	if (value < 0) return;
	int [] argList = {
		OS.XmNminimum, 0,
		OS.XmNmaximum, 0,
		OS.XmNsliderSize, 0,
	};
	/*
	* Feature in Motif.  For some reason, when minimium
	* is set to be greater than or equal to maximum, Motif
	* does not set the minimum.  Instead, the value is
	* changed and the minimum stays the same.  This behavior
	* differs from setting the maximum where the slider size
	* is always decreased to make room for the new maximum.
	* The fix is to decrease the slider to make room for
	* the new minimum.
	*/
	OS.XtGetValues (handle, argList, argList.length / 2);
	if (argList [3] - value - argList [5] < 0) {
		argList [5] = argList [3] - value;
	}
	argList [1] = value;
	boolean warnings = display.getWarnings ();
	display.setWarnings (false);
	OS.XtSetValues (handle, argList, argList.length / 2);
	display.setWarnings (warnings);
}
/**
 * Sets the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected to the argument, which must be at least
 * one.
 *
 * @param value the page increment (must be greater than zero)
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setPageIncrement (int value) {
	checkWidget();
	if (value < 1) return;
	int [] argList = {OS.XmNpageIncrement, value};
	OS.XtSetValues (handle, argList, argList.length / 2);
}
/**
 * Sets the single <em>selection</em> that is the receiver's
 * value to the argument which must be greater than or equal
 * to zero.
 *
 * @param selection the new selection (must be zero or greater)
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setSelection (int selection) {
	checkWidget();
	int [] argList = {OS.XmNvalue, selection};
	boolean warnings = display.getWarnings ();
	display.setWarnings (false);
	OS.XtSetValues (handle, argList, argList.length / 2);
	display.setWarnings (warnings);
}
/**
 * Sets the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.  This new
 * value will be ignored if it is less than one, and will be
 * clamped if it exceeds the receiver's current range.
 *
 * @param value the new thumb value, which must be at least one and not
 * larger than the size of the current range
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setThumb (int value) {
	checkWidget();
	if (value < 1) return;
	int [] argList = {OS.XmNminimum, 0, OS.XmNmaximum, 0};
	OS.XtGetValues (handle, argList, argList.length / 2);
	value = Math.min (value, argList [3] - argList [1]);
	int [] argList2 = {OS.XmNsliderSize, value};
	boolean warnings = display.getWarnings ();
	display.setWarnings (false);
	OS.XtSetValues (handle, argList2, argList2.length / 2);
	display.setWarnings (warnings);
}
/**
 * Sets the receiver's selection, minimum value, maximum
 * value, thumb, increment and page increment all at once.
 * <p>
 * Note: This is similar to setting the values individually
 * using the appropriate methods, but may be implemented in a 
 * more efficient fashion on some platforms.
 * </p>
 *
 * @param selection the new selection value
 * @param minimum the new minimum value
 * @param maximum the new maximum value
 * @param thumb the new thumb value
 * @param increment the new increment value
 * @param pageIncrement the new pageIncrement value
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setValues (int selection, int minimum, int maximum, int thumb, int increment, int pageIncrement) {
	checkWidget();
	if (minimum < 0) return;
	if (maximum < 0) return;
	if (thumb < 1) return;
	if (increment < 1) return;
	if (pageIncrement < 1) return;
	thumb = Math.min (thumb, maximum - minimum);
	int [] argList = {
		OS.XmNvalue, selection,
		OS.XmNminimum, minimum,
		OS.XmNmaximum, maximum,
		OS.XmNsliderSize, thumb,
		OS.XmNincrement, increment,
		OS.XmNpageIncrement, pageIncrement,
	};
	boolean warnings = display.getWarnings ();
	display.setWarnings (false);
	OS.XtSetValues (handle, argList, argList.length / 2);
	display.setWarnings (warnings);
}
/**
 * Marks the receiver as visible if the argument is <code>true</code>,
 * and marks it invisible otherwise. 
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, marking
 * it visible may not actually cause it to be displayed.
 * </p>
 *
 * @param visible the new visibility state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setVisible (boolean visible) {
	checkWidget();
	if (parent.setScrollBarVisible (this, visible)) {
		sendEvent (visible ? SWT.Show : SWT.Hide);
		parent.sendEvent (SWT.Resize);
	}
}
int XButtonPress (int w, int client_data, int call_data, int continue_to_dispatch) {
	int result = super.XButtonPress (w, client_data, call_data, continue_to_dispatch);
	if (result != 0) return result;
	dragSent = false;
	return result;
}
int XmNdecrementCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.ARROW_UP);
	return 0;
}
int XmNdragCallback (int w, int client_data, int call_data) {
	dragSent = true;
	sendScrollEvent (SWT.DRAG);
	return 0;
}
int XmNincrementCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.ARROW_DOWN);
	return 0;
}
int XmNpageDecrementCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.PAGE_UP);
	return 0;
}
int XmNpageIncrementCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.PAGE_DOWN);
	return 0;
}
int XmNtoBottomCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.END);
	return 0;
}
int XmNtoTopCallback (int w, int client_data, int call_data) {
	sendScrollEvent (SWT.HOME);
	return 0;
}
int XmNvalueChangedCallback (int w, int client_data, int call_data) {
	if (!dragSent){
		sendScrollEvent (SWT.DRAG);
		dragSent = false;
	}
	sendScrollEvent (SWT.NONE);
	return 0;
}
}