On X11, this is done by inspecting the _NET_ACTIVE_WINDOW property
on the root window, as described in the
Extended Window Manager Hints.
If there is no currently currently active
window, or the window manager does not support the
_NET_ACTIVE_WINDOW hint, this function returns null.
On other platforms, this function may return null, depending on whether
it is implementable on that platform.
Returns the screen’s currently active window.
On X11, this is done by inspecting the _NET_ACTIVE_WINDOW property on the root window, as described in the Extended Window Manager Hints. If there is no currently currently active window, or the window manager does not support the _NET_ACTIVE_WINDOW hint, this function returns null.
On other platforms, this function may return null, depending on whether it is implementable on that platform.
The returned window should be unrefed using gobject.object.ObjectWrap.unref when no longer needed.