Some work toward posframe on wayland

Some work toward posframe on wayland

* src/pgtkterm.c (flip_cr_context, x_set_offset): update for new functionality
(pgtk_set_window_size): remove dead code
(x_set_parent_frame): cleanup trace code
(pgtk_cr_update_surface_desired_size): add comment

* src/pgtkmenu.c (Fmenu_or_popup_active_p):

* src/pgtkfns.c (pgtk_frame_parm_handlers, Fx_create_frame):

* src/gtkutil.c (xg_create_frame_widgets, x_wm_set_size_hint):

* src/gtkutil.c (xg_create_frame_widgets):

hacky GTK offsets taht will need better calculations

Get parent frame's editor widget allocation for the offset

Fix child-frame offsets for negative values

Add some function comments around the new double context handling