On Mac OS, the screen coordinates start with (0, 0) at the upper left of the menu bar. In contrast, move in top-level-window<%> considers (0, 0) to be below the menu bar. See also get-display-left-top-inset.

The enable state of a window can be changed by enabling a parent window, and such changes do not go through this method; use on-superwindow-enable to monitor enable state changes.

If enable? is true, the window is enabled, otherwise it is disabled.

See also on-focus.

Note that on Unix, keyboard focus can move to the menu bar when the user is selecting a menu item.

The current keyboard focus window can be changed by the user, and such changes do not go through this method; use on-focus to monitor focus changes.

• Windows: HWND

• Mac OS: NSView

• Unix: GtkWidget

See also get-handle.

The client size is returned as two values: width and height (in pixels).

See also reflow-container.

• Windows: HWND

• Mac OS: NSWindow for a top-level-window<%> object, NSView for other windows

• Unix: GtkWidget

See also get-client-handle.

See also reflow-container.

A label string may contain &s, which serve as keyboard navigation annotations for controls on Windows and Unix. The ampersands are not part of the displayed label of a control; instead, ampersands are removed in the displayed label (on all platforms), and any character preceding an ampersand is underlined (Windows and Unix) indicating that the character is a mnemonic for the control. Double ampersands are converted into a single ampersand (with no displayed underline). See also on-traverse-char.

If the window does not have a label, #f is returned.

• If the label includes (&c) for any character c, then the sequenece and any surrounding whitespace is removed.

• If the label contains &c for any character c, the & is removed.

• If the label contains a tab character, then the tab character and all following characters are removed.

See also button%’s handling of labels.

If the window has no label or the window’s label is not a string, #f is returned.

The geometry is returned as two values: width and height (in pixels).

See also reflow-container.

See also reflow-container.

See also reflow-container.

See also reflow-container.

On Mac OS, when the application is running and user double-clicks an application-handled file or drags a file onto the application’s icon, the main thread’s application file handler is called (see application-file-handler). The default handler calls the on-drop-file method of the most-recently activated frame if drag-and-drop is enabled for that frame, independent of the frame’s eventspace (but the method is called in the frame’s eventspace’s handler thread). When the application is not running, the filenames are provided as command-line arguments.

Note that on Unix, keyboard focus can move to the menu bar when the user is selecting a menu item.

Default implementation: Does nothing.

Default implementation: Does nothing.

Default implementation: Does nothing.

The event argument is the event that was generated for the receiver window.

The atomicity limitation on-subwindow-event applies to on-subwindow-char as well. That is, an insufficiently cooperative on-subwindow-char method can effectively disable a control’s handling of key events, even when it returns #f

BEWARE: The default on-subwindow-char in frame% and on-subwindow-char in dialog% methods consume certain keyboard events (e.g., arrow keys, Enter) used for navigating within the window. Because the top-level window gets the first chance to handle the keyboard event, some events never reach the “receiver” child unless the default frame or dialog method is overridden.

Default implementation: Returns #f.

The event argument is the event that was generated for the receiver window.

If the on-subwindow-event method chain does not complete atomically (i.e., without requiring other threads to run) or does not complete fast enough, then the corresponding event may not be delivered to a target control, such as a button. In other words, an insufficiently cooperative on-subwindow-event method can effectively disable a control’s handling of mouse events, even when it returns #f.

Default implementation: Returns #f.

Default implementation: Does nothing.

This method is not called when the window is initially created; it is called only after a change from the window’s initial enable state. Furthermore, if an enable notification event is queued for the window and it reverts its enabled state before the event is dispatched, then the dispatch is canceled.

If the enable state of a window’s ancestor changes while the window is deleted (e.g., because it was removed with delete-child), then no enable events are queued for the deleted window. But if the window is later re-activated into an enable state that is different from the window’s state when it was de-activated, then an enable event is immediately queued.

Default implementation: Does nothing.

This method is not called when the window is initially created; it is called only after a change from the window’s initial visibility. Furthermore, if a show notification event is queued for the window and it reverts its visibility before the event is dispatched, then the dispatch is canceled.

Default implementation: Does nothing.

The menu is popped up within the window at position (x, y).

If a window does not have a cursor, it uses the cursor of its parent. Frames and dialogs start with the standard arrow cursor, and text fields start with an I-beam cursor. All other windows are created without a cursor.

If the window was not created with a label, or if the window was created with a non-string label, l is ignored.

See get-label for more information.

The visibility of a window can be changed by the user clicking the window’s close box, for example, and such changes do not go through this method; use on-superwindow-show or on-close to monitor visibility changes.

If show? is #f, the window is hidden. Otherwise, the window is shown.

• 'one — wheel events are always reported for a single step, where the window accumulates increments until it reaches a full step, and where it generates separate events for multi-step accumulations.

• 'integer — wheel events are always reported as integer-sized steps, where fractional steps are accumulated and preserved as needed to reach integer increments.

• 'fraction — wheel events are reported as positive real values immediately as received from the underlying platform.

The default wheel-event mode is 'one, except that editor-canvas% initializes the wheel-event mode to 'integer.