* frame.c (Qalpha): Add a new frame parameter `alpha'.
(Vframe_alpha_lower_limit) : New variable.
- (x_set_alpha): Add function.
+ (x_set_alpha): New function.
* frame.h (Qalpha, Vframe_parameter_lower_limit): Export them.
* xfns.c (x-create-frame, Qalpha):
Initialize the frame parameter `alpha'.
- * xterm.c (x_set_frame_alpha): Add function.
+ * xterm.c (OPAQUE, OPACITY): New.
+ (x_set_frame_alpha): New function.
+ (frame_highlight, frame_unhighlight): Call x_set_frame_alpha.
* macfns.c (mac_frame_parm_handlers): A null handler for x_set_alpha.
* w32fns.c (w32_frame_parm_handlers): Likewise.