GdkWindowset_geometry_hints

Sets the geometry hints for window. Hints flagged in geom_mask are set, hints not flagged in geom_mask are unset. To unset all hints, use a geom_mask of 0 and a geometry of NULL.

This function provides hints to the windowing system about acceptable sizes for a toplevel window. The purpose of this is to constrain user resizing, but the windowing system will typically (but is not required to) also constrain the current size of the window to the provided values and constrain programatic resizing via gdk_window_resize() or gdk_window_move_resize().

Note that on X11, this effect has no effect on windows of type GDK_WINDOW_TEMP or windows where override redirect has been turned on via gdk_window_set_override_redirect() since these windows are not resizable by the user.

Since you can’t count on the windowing system doing the constraints for programmatic resizes, you should generally call gdk_window_constrain_size() yourself to determine appropriate sizes.