14.1.6 Setting and Reading the WM_HINTS Property

Xlib provides functions that you can use to set and read the WM_HINTS property for a given window. These functions use the flags and the XWMHints structure, as defined in the X11/Xutil.h header file.

To allocate an XWMHints structure, use XAllocWMHints().

The XWMHints structure contains:

/* Window manager hints mask bits */

#define	InputHint	(1L << 0)
#define	StateHint	(1L << 1)
#define	IconPixmapHint	(1L << 2)
#define	IconWindowHint	(1L << 3)
#define	IconPositionHint	(1L << 4)
#define	IconMaskHint	(1L << 5)
#define	WindowGroupHint	(1L << 6)
#define	UrgencyHint	(1L << 8)
#define	AllHints 	(InputHint|StateHint|IconPixmapHint|IconWindowHint|IconPositionHint|IconMaskHint|WindowGroupHint)

/* Values */

typedef struct {
	long flags;		/* marks which fields in this structure are defined */
	Bool input;		/* does this application rely on the window manager to
				   get keyboard input? */
	int initial_state;	/* see below */
	Pixmap icon_pixmap;	/* pixmap to be used as icon */
	Window icon_window;	/* window to be used as icon */
	int icon_x, icon_y;	/* initial position of icon */
	Pixmap icon_mask;	/* pixmap to be used as mask for icon_pixmap */
	XID window_group;	/* id of related window group */
	/* this structure may be extended in the future */
} XWMHints;

The input member is used to communicate to the window manager the input focus model used by the application. Applications that expect input but never explicitly set focus to any of their subwindows (that is, use the push model of focus management), such as X Version 10 style applications that use real-estate driven focus, should set this member to True. Similarly, applications that set input focus to their subwindows only when it is given to their top-level window by a window manager should also set this member to True. Applications that manage their own input focus by explicitly setting focus to one of their subwindows whenever they want keyboard input (that is, use the pull model of focus management) should set this member to False. Applications that never expect any keyboard input also should set this member to False.

Pull model window managers should make it possible for push model applications to get input by setting input focus to the top-level windows of applications whose input member is True. Push model window managers should make sure that pull model applications do not break them by resetting input focus to PointerRoot when it is appropriate (for example, whenever an application whose input member is False sets input focus to one of its subwindows).

The definitions for the initial_state flag are:

#define	WithdrawnState	0
#define	NormalState	1	/* most applications start this way */
#define	IconicState	3	/* application wants to start as an icon */
The icon_mask specifies which pixels of the icon_pixmap should be used as the icon. This allows for nonrectangular icons. Both icon_pixmap and icon_mask must be bitmaps. The icon_window lets an application provide a window for use as an icon for window managers that support such use. The window_group lets you specify that this window belongs to a group of other windows. For example, if a single application manipulates multiple top-level windows, this allows you to provide enough information that a window manager can iconify all of the windows rather than just the one window.

The UrgencyHint flag, if set in the flags field, indicates that the client deems the window contents to be urgent, requiring the timely response of the user. The window manager will make some effort to draw the user's attention to this window while this flag is set. The client must provide some means by which the user can cause the urgency flag to be cleared (either mitigating the condition that made the window urgent or merely shutting off the alarm) or the window to be withdrawn.

To set a window's WM_HINTS property, use XSetWMHints().

To read a window's WM_HINTS property, use XGetWMHints().

Next: Setting and Reading the WM_NORMAL_HINTS Property

Christophe Tronche, ch@tronche.com