XGetInputFocus

Syntax

XGetInputFocus(display, focus_return, revert_to_return)
      Display *display;
      Window *focus_return;
      int *revert_to_return;

display	Specifies the connection to the X server.
focus_return	Returns the focus window, PointerRoot, or None.
revert_to_return	Returns the current focus state (RevertToParent, RevertToPointerRoot, or RevertToNone).

The XGetInputFocus() function returns the focus window and the current focus state.