SYNTAX
int XSetInputFocus(Display *display, Window focus, int  revert_to, Time time);
int XGetInputFocus(Display *display, Window *focus_return, int * revert_to_return);
 
DESCRIPTION
 The  
XSetInputFocus function changes the input focus and the last-focus-change time. It has no effect if the specified time is earlier than the current last-focus-change time or is later than the current X server time. Otherwise, the last-focus-change time is set to the specified time ( 
CurrentTime is replaced by the current X server time).  
XSetInputFocus causes the X server to generate  
FocusIn and  
FocusOut events.
Depending on the focus argument, the following occurs:
- 
•
- 
If focus is  None, all keyboard events are discarded until a new focus window is set, and the revert_to argument is ignored.
- 
•
- 
If focus is a window, it becomes the 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 as usual. Otherwise, the event is reported relative to the focus window.
- 
•
- 
If focus is  PointerRoot, the focus window is dynamically taken to be the root window of whatever screen the pointer is on at each keyboard event. In this case, the revert_to argument is ignored.
The specified focus window must be viewable at the time  XSetInputFocus is called, or a  BadMatch error results. If the focus window later becomes not viewable, the X server evaluates the revert_to argument to determine the new focus window as follows:
- 
•
- 
If revert_to is  RevertToParent, the focus reverts to the parent (or the closest viewable ancestor), and the new revert_to value is taken to be  RevertToNone.
- 
•
- 
If revert_to is  RevertToPointerRoot or  RevertToNone, the focus reverts to  PointerRoot or  None, respectively. When the focus reverts, the X server generates  FocusIn and  FocusOut events, but the last-focus-change time is not affected.
XSetInputFocus can generate  BadMatch,  BadValue, and  BadWindow errors.
The  XGetInputFocus function returns the focus window and the current focus state.