Make gdk_window_move_to_rect() public
Submitted by Jan Horak
Firefox in Wayland is unable to place popup menus correctly because it does no longer knows the absolute position of the main window (this with screen dimensions was used to avoid placing popups out of screen).
GtkMenu uses gdk_window_move_to_rect() to place menus correctly but it is not exported. We need that for the implementation of Firefox menus in wayland. Please consider exporting this symbol.