Control

Control is the abstract superclass of all windowed user interface classes. <p> <dl> <dt><b>Styles:</b> <dd>BORDER</dd> <dd>LEFT_TO_RIGHT, RIGHT_TO_LEFT</dd> <dt><b>Events:</b> <dd>DragDetect, FocusIn, FocusOut, Help, KeyDown, KeyUp, MenuDetect, MouseDoubleClick, MouseDown, MouseEnter, MouseExit, MouseHover, MouseUp, MouseMove, Move, Paint, Resize, Traverse</dd> </dl> </p><p> Only one of LEFT_TO_RIGHT or RIGHT_TO_LEFT may be specified. </p><p> IMPORTANT: This class is intended to be subclassed <em>only</em> within the SWT implementation. </p>

@see <a href="http://www.eclipse.org/swt/snippets/#control">Control snippets</a> @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>

abstract

class Control : Widget , Drawable {

GtkWidget* fixedHandle;

GdkWindow* redrawWindow;

GdkWindow* enableWindow;

int drawCount;

Composite parent;

Cursor cursor;

Menu menu;

Image backgroundImage;

Font font;

Region region;

String toolTipText;

Object layoutData;

Accessible accessible;

this(Composite parent, int style);

bool print(GC gc);

Point computeSize(int wHint, int hHint);

Point computeSize(int wHint, int hHint, bool changed);

Accessible getAccessible();

Rectangle getBounds();

void setBounds(Rectangle rect);

void setBounds(int x, int y, int width, int height);

Point getLocation();

void setLocation(Point location);

void setLocation(int x, int y);

Point getSize();

void setSize(Point size);

void setRegion(Region region);

void setSize(int width, int height);

void moveAbove(Control control);

void moveBelow(Control control);

void pack();

void pack(bool changed);

void setLayoutData(Object layoutData);

Point toControl(int x, int y);

Point toControl(Point point);

Point toDisplay(int x, int y);

Point toDisplay(Point point);

void addControlListener(ControlListener listener);

void addDragDetectListener(DragDetectListener listener);

void addFocusListener(FocusListener listener);

void addHelpListener(HelpListener listener);

void addKeyListener(KeyListener listener);

void addMenuDetectListener(MenuDetectListener listener);

void addMouseListener(MouseListener listener);

void addMouseMoveListener(MouseMoveListener listener);

void addMouseTrackListener(MouseTrackListener listener);

void addMouseWheelListener(MouseWheelListener listener);

void addPaintListener(PaintListener listener);

void addTraverseListener(TraverseListener listener);

void removeControlListener(ControlListener listener);

void removeDragDetectListener(DragDetectListener listener);

void removeFocusListener(FocusListener listener);

void removeHelpListener(HelpListener listener);

void removeKeyListener(KeyListener listener);

void removeMenuDetectListener(MenuDetectListener listener);

void removeMouseListener(MouseListener listener);

void removeMouseMoveListener(MouseMoveListener listener);

void removeMouseTrackListener(MouseTrackListener listener);

void removeMouseWheelListener(MouseWheelListener listener);

void removePaintListener(PaintListener listener);

void removeTraverseListener(TraverseListener listener);

bool dragDetect(Event event);

bool dragDetect(MouseEvent event);

bool forceFocus();

Color getBackground();

Image getBackgroundImage();

int getBorderWidth();

Cursor getCursor();

bool getDragDetect();

bool getEnabled();

Font getFont();

Color getForeground();

Object getLayoutData();

Menu getMenu();

org.eclipse.swt.widgets.Monitor.Monitor getMonitor();

Composite getParent();

Region getRegion();

Shell getShell();

String getToolTipText();

bool getVisible();

GdkGC* internal_new_GC(GCData data);

void internal_dispose_GC(GdkGC* gdkGC, GCData data);

bool isReparentable();

bool isEnabled();

bool isFocusControl();

bool isVisible();

void redraw();

void redraw(int x, int y, int width, int height, bool all);

void setBackground(Color color);

void setBackgroundImage(Image image);

void setCapture(bool capture);

void setCursor(Cursor cursor);

void setDragDetect(bool dragDetect);

void setEnabled(bool enabled);

bool setFocus();

void setFont(Font font);

void setForeground(Color color);

void setMenu(Menu menu);

bool setParent(Composite parent);

void setRedraw(bool redraw);

void setToolTipText(String str);

void setVisible(bool visible);

bool traverse(int traversal);

void update();

}

Constructors

this this(Composite parent, int style): Constructs a new instance of this class given its parent and a style value describing its behavior and appearance. <p> The style value is either one of the style constants defined in class <code>SWT</code> which is applicable to instances of this class, or must be built by <em>bitwise OR</em>'ing together (that is, using the <code>int</code> "|" operator) two or more of those <code>SWT</code> style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses. </p>

Members

Functions

addControlListener void addControlListener(ControlListener listener): Adds the listener to the collection of listeners who will be notified when the control is moved or resized, by sending it one of the messages defined in the <code>ControlListener</code> interface.
addDragDetectListener void addDragDetectListener(DragDetectListener listener): Adds the listener to the collection of listeners who will be notified when a drag gesture occurs, by sending it one of the messages defined in the <code>DragDetectListener</code> interface.
addFocusListener void addFocusListener(FocusListener listener): Adds the listener to the collection of listeners who will be notified when the control gains or loses focus, by sending it one of the messages defined in the <code>FocusListener</code> interface.
addHelpListener void addHelpListener(HelpListener listener): Adds the listener to the collection of listeners who will be notified when help events are generated for the control, by sending it one of the messages defined in the <code>HelpListener</code> interface.
addKeyListener void addKeyListener(KeyListener listener): Adds the listener to the collection of listeners who will be notified when keys are pressed and released on the system keyboard, by sending it one of the messages defined in the <code>KeyListener</code> interface. <p> When a key listener is added to a control, the control will take part in widget traversal. By default, all traversal keys (such as the tab key and so on) are delivered to the control. In order for a control to take part in traversal, it should listen for traversal events. Otherwise, the user can traverse into a control but not out. Note that native controls such as table and tree implement key traversal in the operating system. It is not necessary to add traversal listeners for these controls, unless you want to override the default traversal. </p> @param listener the listener which should be notified
addMenuDetectListener void addMenuDetectListener(MenuDetectListener listener): Adds the listener to the collection of listeners who will be notified when the platform-specific context menu trigger has occurred, by sending it one of the messages defined in the <code>MenuDetectListener</code> interface.
addMouseListener void addMouseListener(MouseListener listener): Adds the listener to the collection of listeners who will be notified when mouse buttons are pressed and released, by sending it one of the messages defined in the <code>MouseListener</code> interface.
addMouseMoveListener void addMouseMoveListener(MouseMoveListener listener): Adds the listener to the collection of listeners who will be notified when the mouse moves, by sending it one of the messages defined in the <code>MouseMoveListener</code> interface.
addMouseTrackListener void addMouseTrackListener(MouseTrackListener listener): Adds the listener to the collection of listeners who will be notified when the mouse passes or hovers over controls, by sending it one of the messages defined in the <code>MouseTrackListener</code> interface.
addMouseWheelListener void addMouseWheelListener(MouseWheelListener listener): Adds the listener to the collection of listeners who will be notified when the mouse wheel is scrolled, by sending it one of the messages defined in the <code>MouseWheelListener</code> interface.
addPaintListener void addPaintListener(PaintListener listener): Adds the listener to the collection of listeners who will be notified when the receiver needs to be painted, by sending it one of the messages defined in the <code>PaintListener</code> interface.
addTraverseListener void addTraverseListener(TraverseListener listener): Adds the listener to the collection of listeners who will be notified when traversal events occur, by sending it one of the messages defined in the <code>TraverseListener</code> interface.
computeSize Point computeSize(int wHint, int hHint): Returns the preferred size of the receiver. <p> The <em>preferred size</em> of a control is the size that it would best be displayed at. The width hint and height hint arguments allow the caller to ask a control questions such as "Given a particular width, how high does the control need to be to show all of the contents?" To indicate that the caller does not wish to constrain a particular dimension, the constant <code>SWT.DEFAULT</code> is passed for the hint. </p>
computeSize Point computeSize(int wHint, int hHint, bool changed): Returns the preferred size of the receiver. <p> The <em>preferred size</em> of a control is the size that it would best be displayed at. The width hint and height hint arguments allow the caller to ask a control questions such as "Given a particular width, how high does the control need to be to show all of the contents?" To indicate that the caller does not wish to constrain a particular dimension, the constant <code>SWT.DEFAULT</code> is passed for the hint. </p><p> If the changed flag is <code>true</code>, it indicates that the receiver's <em>contents</em> have changed, therefore any caches that a layout manager containing the control may have been keeping need to be flushed. When the control is resized, the changed flag will be <code>false</code>, so layout manager caches can be retained. </p>
dragDetect bool dragDetect(Event event): Detects a drag and drop gesture. This method is used to detect a drag gesture when called from within a mouse down listener.
dragDetect bool dragDetect(MouseEvent event): Detects a drag and drop gesture. This method is used to detect a drag gesture when called from within a mouse down listener.
forceFocus bool forceFocus(): Forces the receiver to have the <em>keyboard focus</em>, causing all keyboard events to be delivered to it.
getAccessible Accessible getAccessible(): Returns the accessible object for the receiver. If this is the first time this object is requested, then the object is created and returned.
getBackground Color getBackground(): Returns the receiver's background color.
getBackgroundImage Image getBackgroundImage(): Returns the receiver's background image.
getBorderWidth int getBorderWidth(): Returns the receiver's border width.
getBounds Rectangle getBounds(): Returns a rectangle describing the receiver's size and location relative to its parent (or its display if its parent is null), unless the receiver is a shell. In this case, the location is relative to the display.
getCursor Cursor getCursor(): Returns the receiver's cursor, or null if it has not been set. <p> When the mouse pointer passes over a control its appearance is changed to match the control's cursor. </p>
getDragDetect bool getDragDetect(): Returns <code>true</code> if the receiver is detecting drag gestures, and <code>false</code> otherwise.
getEnabled bool getEnabled(): 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.
getFont Font getFont(): Returns the font that the receiver will use to paint textual information.
getForeground Color getForeground(): Returns the foreground color that the receiver will use to draw.
getLayoutData Object getLayoutData(): Returns layout data which is associated with the receiver.
getLocation Point getLocation(): Returns a point describing the receiver's location relative to its parent (or its display if its parent is null), unless the receiver is a shell. In this case, the point is relative to the display.
getMenu Menu getMenu(): Returns the receiver's pop up menu if it has one, or null if it does not. All controls may optionally have a pop up menu that is displayed when the user requests one for the control. The sequence of key strokes, button presses and/or button releases that are used to request a pop up menu is platform specific.
getMonitor org.eclipse.swt.widgets.Monitor.Monitor getMonitor(): Returns the receiver's monitor.
getParent Composite getParent(): Returns the receiver's parent, which must be a <code>Composite</code> or null when the receiver is a shell that was created with null or a display for a parent.
getRegion Region getRegion(): Returns the region that defines the shape of the control, or null if the control has the default shape.
getShell Shell getShell(): Returns the receiver's shell. For all controls other than shells, this simply returns the control's nearest ancestor shell. Shells return themselves, even if they are children of other shells.
getSize Point getSize(): 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.
getToolTipText String getToolTipText(): Returns the receiver's tool tip text, or null if it has not been set.
getVisible bool getVisible(): 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>
internal_dispose_GC void internal_dispose_GC(GdkGC* gdkGC, GCData data): Invokes platform specific functionality to dispose a GC handle. <p> <b>IMPORTANT:</b> This method is <em>not</em> part of the public API for <code>Control</code>. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code. </p>
internal_new_GC GdkGC* internal_new_GC(GCData data): Invokes platform specific functionality to allocate a new GC handle. <p> <b>IMPORTANT:</b> This method is <em>not</em> part of the public API for <code>Control</code>. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code. </p>
isEnabled bool isEnabled(): Returns <code>true</code> if the receiver is enabled and all ancestors up to and including the receiver's nearest ancestor shell are enabled. Otherwise, <code>false</code> is returned. A disabled control is typically not selectable from the user interface and draws with an inactive or "grayed" look.
isFocusControl bool isFocusControl(): Returns <code>true</code> if the receiver has the user-interface focus, and <code>false</code> otherwise.
isReparentable bool isReparentable(): Returns <code>true</code> if the underlying operating system supports this reparenting, otherwise <code>false</code>
isVisible bool isVisible(): Returns <code>true</code> if the receiver is visible and all ancestors up to and including the receiver's nearest ancestor shell are visible. Otherwise, <code>false</code> is returned.
moveAbove void moveAbove(Control control): Moves the receiver above the specified control in the drawing order. If the argument is null, then the receiver is moved to the top of the drawing order. The control at the top of the drawing order will not be covered by other controls even if they occupy intersecting areas.
moveBelow void moveBelow(Control control): Moves the receiver below the specified control in the drawing order. If the argument is null, then the receiver is moved to the bottom of the drawing order. The control at the bottom of the drawing order will be covered by all other controls which occupy intersecting areas.
pack void pack(): Causes the receiver to be resized to its preferred size. For a composite, this involves computing the preferred size from its layout, if there is one.
pack void pack(bool changed): Causes the receiver to be resized to its preferred size. For a composite, this involves computing the preferred size from its layout, if there is one. <p> If the changed flag is <code>true</code>, it indicates that the receiver's <em>contents</em> have changed, therefore any caches that a layout manager containing the control may have been keeping need to be flushed. When the control is resized, the changed flag will be <code>false</code>, so layout manager caches can be retained. </p>
print bool print(GC gc): Prints the receiver and all children.
redraw void redraw(): Causes the entire bounds of the receiver to be marked as needing to be redrawn. The next time a paint request is processed, the control will be completely painted, including the background.
redraw void redraw(int x, int y, int width, int height, bool all): Causes the rectangular area of the receiver specified by the arguments to be marked as needing to be redrawn. The next time a paint request is processed, that area of the receiver will be painted, including the background. If the <code>all</code> flag is <code>true</code>, any children of the receiver which intersect with the specified area will also paint their intersecting areas. If the <code>all</code> flag is <code>false</code>, the children will not be painted.
removeControlListener void removeControlListener(ControlListener listener): Removes the listener from the collection of listeners who will be notified when the control is moved or resized.
removeDragDetectListener void removeDragDetectListener(DragDetectListener listener): Removes the listener from the collection of listeners who will be notified when a drag gesture occurs.
removeFocusListener void removeFocusListener(FocusListener listener): Removes the listener from the collection of listeners who will be notified when the control gains or loses focus.
removeHelpListener void removeHelpListener(HelpListener listener): Removes the listener from the collection of listeners who will be notified when the help events are generated for the control.
removeKeyListener void removeKeyListener(KeyListener listener): Removes the listener from the collection of listeners who will be notified when keys are pressed and released on the system keyboard.
removeMenuDetectListener void removeMenuDetectListener(MenuDetectListener listener): Removes the listener from the collection of listeners who will be notified when the platform-specific context menu trigger has occurred.
removeMouseListener void removeMouseListener(MouseListener listener): Removes the listener from the collection of listeners who will be notified when mouse buttons are pressed and released.
removeMouseMoveListener void removeMouseMoveListener(MouseMoveListener listener): Removes the listener from the collection of listeners who will be notified when the mouse moves.
removeMouseTrackListener void removeMouseTrackListener(MouseTrackListener listener): Removes the listener from the collection of listeners who will be notified when the mouse passes or hovers over controls.
removeMouseWheelListener void removeMouseWheelListener(MouseWheelListener listener): Removes the listener from the collection of listeners who will be notified when the mouse wheel is scrolled.
removePaintListener void removePaintListener(PaintListener listener): Removes the listener from the collection of listeners who will be notified when the receiver needs to be painted.
removeTraverseListener void removeTraverseListener(TraverseListener listener): Removes the listener from the collection of listeners who will be notified when traversal events occur.
setBackground void setBackground(Color color): Sets the receiver's background color to the color specified by the argument, or to the default system color for the control if the argument is null. <p> Note: This operation is a hint and may be overridden by the platform. For example, on Windows the background of a Button cannot be changed. </p> @param color the new color (or null)
setBackgroundImage void setBackgroundImage(Image image): Sets the receiver's background image to the image specified by the argument, or to the default system color for the control if the argument is null. The background image is tiled to fill the available space. <p> Note: This operation is a hint and may be overridden by the platform. For example, on Windows the background of a Button cannot be changed. </p> @param image the new image (or null)
setBounds void setBounds(Rectangle rect): Sets the receiver's size and location to the rectangular area specified by the argument. The <code>x</code> and <code>y</code> fields of the rectangle are relative to the receiver's parent (or its display if its parent is null). <p> Note: Attempting to set the width or height of the receiver to a negative number will cause that value to be set to zero instead. </p>
setBounds void setBounds(int x, int y, int width, int height): Sets the receiver's size and location to the rectangular area specified by the arguments. The <code>x</code> and <code>y</code> arguments are relative to the receiver's parent (or its display if its parent is null), unless the receiver is a shell. In this case, the <code>x</code> and <code>y</code> arguments are relative to the display. <p> Note: Attempting to set the width or height of the receiver to a negative number will cause that value to be set to zero instead. </p>
setCapture void setCapture(bool capture): If the argument is <code>true</code>, causes the receiver to have all mouse events delivered to it until the method is called with <code>false</code> as the argument. Note that on some platforms, a mouse button must currently be down for capture to be assigned.
setCursor void setCursor(Cursor cursor): Sets the receiver's cursor to the cursor specified by the argument, or to the default cursor for that kind of control if the argument is null. <p> When the mouse pointer passes over a control its appearance is changed to match the control's cursor. </p>
setDragDetect void setDragDetect(bool dragDetect): Sets the receiver's drag detect state. If the argument is <code>true</code>, the receiver will detect drag gestures, otherwise these gestures will be ignored.
setEnabled void setEnabled(bool enabled): 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.
setFocus bool setFocus(): Causes the receiver to have the <em>keyboard focus</em>, such that all keyboard events will be delivered to it. Focus reassignment will respect applicable platform constraints.
setFont void setFont(Font font): Sets the font that the receiver will use to paint textual information to the font specified by the argument, or to the default font for that kind of control if the argument is null.
setForeground void setForeground(Color color): Sets the receiver's foreground color to the color specified by the argument, or to the default system color for the control if the argument is null. <p> Note: This operation is a hint and may be overridden by the platform. </p> @param color the new color (or null)
setLayoutData void setLayoutData(Object layoutData): Sets the layout data associated with the receiver to the argument.
setLocation void setLocation(Point location): Sets the receiver's location to the point specified by the arguments which are relative to the receiver's parent (or its display if its parent is null), unless the receiver is a shell. In this case, the point is relative to the display.
setLocation void setLocation(int x, int y): Sets the receiver's location to the point specified by the arguments which are relative to the receiver's parent (or its display if its parent is null), unless the receiver is a shell. In this case, the point is relative to the display.
setMenu void setMenu(Menu menu): Sets the receiver's pop up menu to the argument. All controls may optionally have a pop up menu that is displayed when the user requests one for the control. The sequence of key strokes, button presses and/or button releases that are used to request a pop up menu is platform specific. <p> Note: Disposing of a control that has a pop up menu will dispose of the menu. To avoid this behavior, set the menu to null before the control is disposed. </p>
setParent bool setParent(Composite parent): Changes the parent of the widget to be the one provided if the underlying operating system supports this feature. Returns <code>true</code> if the parent is successfully changed.
setRedraw void setRedraw(bool redraw): If the argument is <code>false</code>, causes subsequent drawing operations in the receiver to be ignored. No drawing of any kind can occur in the receiver until the flag is set to true. Graphics operations that occurred while the flag was <code>false</code> are lost. When the flag is set to <code>true</code>, the entire widget is marked as needing to be redrawn. Nested calls to this method are stacked. <p> Note: This operation is a hint and may not be supported on some platforms or for some widgets. </p>
setRegion void setRegion(Region region): Sets the shape of the control to the region specified by the argument. When the argument is null, the default shape of the control is restored.
setSize void setSize(Point size): Sets the receiver's size to the point specified by the argument. <p> Note: Attempting to set the width or height of the receiver to a negative number will cause them to be set to zero instead. </p>
setSize void setSize(int width, int height): Sets the receiver's size to the point specified by the arguments. <p> Note: Attempting to set the width or height of the receiver to a negative number will cause that value to be set to zero instead. </p>
setToolTipText void setToolTipText(String str): Sets the receiver's tool tip text to the argument, which may be null indicating that no tool tip text should be shown.
setVisible void setVisible(bool visible): 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>
toControl Point toControl(int x, int y): Returns a point which is the result of converting the argument, which is specified in display relative coordinates, to coordinates relative to the receiver. <p> @param x the x coordinate to be translated @param y the y coordinate to be translated @return the translated coordinates
toControl Point toControl(Point point): Returns a point which is the result of converting the argument, which is specified in display relative coordinates, to coordinates relative to the receiver. <p> @param point the point to be translated (must not be null) @return the translated coordinates
toDisplay Point toDisplay(int x, int y): Returns a point which is the result of converting the argument, which is specified in coordinates relative to the receiver, to display relative coordinates. <p> @param x the x coordinate to be translated @param y the y coordinate to be translated @return the translated coordinates
toDisplay Point toDisplay(Point point): Returns a point which is the result of converting the argument, which is specified in coordinates relative to the receiver, to display relative coordinates. <p> @param point the point to be translated (must not be null) @return the translated coordinates
traverse bool traverse(int traversal): Based on the argument, perform one of the expected platform traversal action. The argument should be one of the constants: <code>SWT.TRAVERSE_ESCAPE</code>, <code>SWT.TRAVERSE_RETURN</code>, <code>SWT.TRAVERSE_TAB_NEXT</code>, <code>SWT.TRAVERSE_TAB_PREVIOUS</code>, <code>SWT.TRAVERSE_ARROW_NEXT</code> and <code>SWT.TRAVERSE_ARROW_PREVIOUS</code>.
update void update(): Forces all outstanding paint requests for the widget to be processed before this method returns. If there are no outstanding paint request, this method does nothing. <p> Note: This method does not cause a redraw. </p>

Inherited Members

handle GtkWidget* handle;: the handle to the OS resource (Warning: This field is platform dependent) <p> <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms and should never be accessed from application code. </p>
addListener void addListener(int eventType, Listener listener): Adds the listener to the collection of listeners who will be notified when an event of the given type occurs. When the event does occur in the widget, the listener is notified by sending it the <code>handleEvent()</code> message. The event type is one of the event constants defined in class <code>SWT</code>.
addDisposeListener void addDisposeListener(DisposeListener listener): Adds the listener to the collection of listeners who will be notified when the widget is disposed. When the widget is disposed, the listener is notified by sending it the <code>widgetDisposed()</code> message.
checkParent void checkParent(Widget parent): Throws an exception if the specified widget can not be used as a parent for the receiver.
checkSubclass void checkSubclass(): Checks that this class can be subclassed. <p> The SWT class library is intended to be subclassed only at specific, controlled points (most notably, <code>Composite</code> and <code>Canvas</code> when implementing new widgets). This method enforces this rule unless it is overridden. </p><p> <em>IMPORTANT:</em> By providing an implementation of this method that allows a subclass of a class which does not normally allow subclassing to be created, the implementer agrees to be fully responsible for the fact that any such subclass will likely fail between SWT releases and will be strongly platform specific. No support is provided for user-written classes which are implemented in this fashion. </p><p> The ability to subclass outside of the allowed SWT classes is intended purely to enable those not on the SWT development team to implement patches in order to get around specific limitations in advance of when those limitations can be addressed by the team. Subclassing should not be attempted without an intimate and detailed understanding of the hierarchy. </p>
checkWidget void checkWidget(): Throws an <code>SWTException</code> if the receiver can not be accessed by the caller. This may include both checks on the state of the receiver and more generally on the entire execution context. This method <em>should</em> be called by widget implementors to enforce the standard SWT invariants. <p> Currently, it is an error to invoke any method (other than <code>isDisposed()</code>) on a widget that has had its <code>dispose()</code> method called. It is also an error to call widget methods from any thread that is different from the thread that created the widget. </p><p> In future releases of SWT, there may be more or fewer error checks and exceptions may be thrown for different reasons. </p>
dispose void dispose(): Disposes of the operating system resources associated with the receiver and all its descendants. After this method has been invoked, the receiver and all descendants will answer <code>true</code> when sent the message <code>isDisposed()</code>. Any internal connections between the widgets in the tree will have been removed to facilitate garbage collection. <p> NOTE: This method is not called recursively on the descendants of the receiver. This means that, widget implementers can not detect when a widget is being disposed of by re-implementing this method, but should instead listen for the <code>Dispose</code> event. </p>
getData Object getData(): Returns the application defined widget data associated with the receiver, or null if it has not been set. The <em>widget data</em> is a single, unnamed field that is stored with every widget. <p> Applications may put arbitrary objects in this field. If the object stored in the widget data needs to be notified when the widget is disposed of, it is the application's responsibility to hook the Dispose event on the widget and do so. </p>
getData Object getData(String key): Returns the application defined property of the receiver with the specified name, or null if it has not been set. <p> Applications may have associated arbitrary objects with the receiver in this fashion. If the objects stored in the properties need to be notified when the widget is disposed of, it is the application's responsibility to hook the Dispose event on the widget and do so. </p>
getDisplay Display getDisplay(): Returns the <code>Display</code> that is associated with the receiver. <p> A widget's display is either provided when it is created (for example, top level <code>Shell</code>s) or is the same as its parent's display. </p>
getListeners Listener[] getListeners(int eventType): Returns an array of listeners who will be notified when an event of the given type occurs. The event type is one of the event constants defined in class <code>SWT</code>.
getStyle int getStyle(): Returns the receiver's style information. <p> Note that the value which is returned by this method <em>may not match</em> the value which was provided to the constructor when the receiver was created. This can occur when the underlying operating system does not support a particular combination of requested styles. For example, if the platform widget used to implement a particular SWT widget always has scroll bars, the result of calling this method would always have the <code>SWT.H_SCROLL</code> and <code>SWT.V_SCROLL</code> bits set. </p>
isDisposed bool isDisposed(): Returns <code>true</code> if the widget has been disposed, and <code>false</code> otherwise. <p> This method gets the dispose state for the widget. When a widget has been disposed, it is an error to invoke any other method using the widget. </p>
isListening bool isListening(int eventType): Returns <code>true</code> if there are any listeners for the specified event type associated with the receiver, and <code>false</code> otherwise. The event type is one of the event constants defined in class <code>SWT</code>.
notifyListeners void notifyListeners(int eventType, Event event): Notifies all of the receiver's listeners for events of the given type that one such event has occurred by invoking their <code>handleEvent()</code> method. The event type is one of the event constants defined in class <code>SWT</code>.
removeListener void removeListener(int eventType, Listener handler): Removes the listener from the collection of listeners who will be notified when an event of the given type occurs. The event type is one of the event constants defined in class <code>SWT</code>.
removeListener void removeListener(int eventType, SWTEventListener handler): Removes the listener from the collection of listeners who will be notified when an event of the given type occurs. <p> <b>IMPORTANT:</b> This method is <em>not</em> part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It should never be referenced from application code. </p>
removeDisposeListener void removeDisposeListener(DisposeListener listener): Removes the listener from the collection of listeners who will be notified when the widget is disposed.
setData void setData(Object data): Sets the application defined widget data associated with the receiver to be the argument. The <em>widget data</em> is a single, unnamed field that is stored with every widget. <p> Applications may put arbitrary objects in this field. If the object stored in the widget data needs to be notified when the widget is disposed of, it is the application's responsibility to hook the Dispose event on the widget and do so. </p>
setData void setData(String key, Object value): Sets the application defined property of the receiver with the specified name to the given value. <p> Applications may associate arbitrary objects with the receiver in this fashion. If the objects stored in the properties need to be notified when the widget is disposed of, it is the application's responsibility to hook the Dispose event on the widget and do so. </p>
toString String toString(): Returns a string containing a concise, human-readable description of the receiver.

From Drawable

internal_new_GC GdkGC* internal_new_GC(GCData data): Invokes platform specific functionality to allocate a new GC handle. <p> <b>IMPORTANT:</b> This method is <em>not</em> part of the public API for <code>Drawable</code>. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code. </p>
internal_dispose_GC void internal_dispose_GC(GdkGC* handle, GCData data): Invokes platform specific functionality to dispose a GC handle. <p> <b>IMPORTANT:</b> This method is <em>not</em> part of the public API for <code>Drawable</code>. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code. </p>

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