XSetInputFocus()														  XSetInputFocus()

Name
  XSetInputFocus - set the keyboard focus window.

Synopsis
  XSetInputFocus(display, focus, revert_to, time)
	Display *display;
	Window focus;
	int revert_to;
	Time time;

Arguments
  display  Specifies a connection to an X server; returned from XOpenDisplay().

  focus    Specifies the ID of the window you want to be the keyboard focus.  Pass the window ID, PointerRoot, or None.

  revert_to
	   Specifies  which  window  the  keyboard  focus  reverts to if the focus window becomes not viewable.  Pass one of these constants:
	   RevertToParent, RevertToPointerRoot, or RevertToNone.  Must not be a window ID.

  time	   Specifies the time when the focus change should take place.	Pass either a timestamp, expressed in milliseconds, or	the  constant
	   CurrentTime.  Also returns the time of the focus change when CurrentTime is specified.

Description
  XSetInputFocus() changes the keyboard focus and the last-focus-change time.  The function has no effect if time is earlier than the current
  last-focus-change time or later than the current X server time.  Otherwise, the last-focus-change time is set to the specified  time,  with
  CurrentTime replaced by the current X server time.

  XSetInputFocus() generates FocusIn and FocusOut events if focus is different from the current focus.

  XSetInputFocus() executes as follows, depending on what value you assign to the focus argument:

  o  If you assign None, all keyboard events are discarded until you set a new focus window.  In this case, revert_to is ignored.

  o  If  you  assign  a  window ID, it becomes the main keyboard's focus window.  If a generated keyboard event would normally be reported to
     this window or one of its inferiors, the event is reported normally; otherwise, the event is reported to the focus window.   The  speci-
     fied  focus window must be viewable at the time of the request (else a BadMatch error).  If the focus window later becomes not viewable,
     the focus window will change to the revert_to argument.

  o  If you assign PointerRoot, the focus window is dynamically taken to be the root window of whatever screen the pointer is on at each key-
     board event.  In this case, revert_to is ignored.	This is the default keyboard focus setting.

  If the focus window later becomes not viewable, XSetInputFocus() evaluates the revert_to argument to determine the new focus window:

  o  If  you  assign  RevertToParent,  the  focus reverts to the parent (or the closest viewable ancestor) automatically with a new revert_to
     argument of RevertToName.

  o  If you assign RevertToPointerRoot or RevertToNone, the focus reverts to that value automatically.	FocusIn and FocusOut events are  gen-
     erated when the focus reverts, but the last focus change time is not affected.

Errors
  BadMatch  focus window not viewable when XSetInputFocus() called.

  BadValue

  BadWindow

See Also
  XQLength(),	XAllowEvents(),   XCheckIfEvent(),   XCheckMaskEvent(),  XCheckTypedEvent(),  XCheckTypedWindowEvent(),  XCheckWindowEvent(),
  XEventsQueued(), XGetInputFocus(), XGetMotionEvents(), XIfEvent(), XMaskEvent(), XNextEvent(),  XPeekEvent(),  XPeekIfEvent(),  XPending(),
  XPutBackEvent(), XSelectInput(), XSendEvent(), XSynchronize(), XWindowEvent().

Xlib - Input Handling														  XSetInputFocus()