(XTread_socket): Don't offset keysym here.

(XTread_socket): Don't offset keysym here.
Special handling for "dead accent" keysyms.

(construct_mouse_click, x_scroll_bar_handle_click)
(XTread_socket): `code' of an event is now an int.

(pixel_to_glyph_coords): New arg NOCLIP.  Callers changed.

(XTread_socket): For MotionNotify, if x_mouse_grabbed, use last_mouse_frame.
(construct_mouse_click): Set last_mouse_frame.
(XTmouse_position): If x_mouse_grabbed, use last_mouse_frame.

(x_calc_absolute_position): Borderwidth must be doubled
before subtracting from width to get correct value.