bug#13426: Frame parameter fullscreen and maximized

[Juri Linkov <juri@jurta.org>]

There are two problems discovered at
http://lists.gnu.org/archive/html/emacs-devel/2013-01/msg00203.html

1. On non-GTK builds when the Gnome system key M-f10 maximizes the frame,
   Emacs doesn't reflect this change in the frame parameter `fullscreen'.

   The test case that demonstrates this problem:

   1. emacs -Q
   2. Eval (frame-parameter nil 'fullscreen) => nil
   3. Maximize the frame using Gnome system keys.
   4. Eval (frame-parameter nil 'fullscreen) => nil
   5. Maximize the frame using `M-x toggle-frame-maximized RET'
   6. Eval (frame-parameter nil 'fullscreen) => 'maximized

   Running xprop on the maximized frame outputs:
   _NET_WM_STATE(ATOM) = _NET_WM_STATE_MAXIMIZED_VERT, _NET_WM_STATE_MAXIMIZED_HORZ

2. On GTK builds there is another problem: evaluating

   (set-frame-parameter nil 'fullscreen 'fullscreen)

   modifies the frame parameter `fullscreen' to `fullboth',
   not to `fullscreen' as requested.  In this case xprop outputs:
   _NET_WM_STATE(ATOM) = _NET_WM_STATE_FULLSCREEN

   Second call of (set-frame-parameter nil 'fullscreen 'fullscreen)
   modifies the frame parameter `fullscreen' from `fullboth' to `fullscreen'.

   So to go to `fullscreen' requires two calls of
   (set-frame-parameter nil 'fullscreen 'fullscreen)

   Maybe the second problem could be fixed with a patch like below where
   `toggle-frame-fullscreen' checks for `fullboth' as an alias for `fullscreen':

=== modified file 'lisp/frame.el'
--- lisp/frame.el	2013-01-03 00:36:36 +0000
+++ lisp/frame.el	2013-01-13 10:13:09 +0000
@@ -1666,7 +1666,7 @@ (defun toggle-frame-maximized ()
 after disabling fullscreen mode.
 See also `toggle-frame-fullscreen'."
   (interactive)
-  (if (eq (frame-parameter nil 'fullscreen) 'fullscreen)
+  (if (memq (frame-parameter nil 'fullscreen) '(fullscreen fullboth))
       (modify-frame-parameters
        nil
        `((maximized
@@ -1690,10 +1690,10 @@ (defun toggle-frame-fullscreen ()
   (modify-frame-parameters
    nil
    `((maximized
-      . ,(unless (eq (frame-parameter nil 'fullscreen) 'fullscreen)
+      . ,(unless (memq (frame-parameter nil 'fullscreen) '(fullscreen fullboth))
 	   (frame-parameter nil 'fullscreen)))
      (fullscreen
-      . ,(if (eq (frame-parameter nil 'fullscreen) 'fullscreen)
+      . ,(if (memq (frame-parameter nil 'fullscreen) '(fullscreen fullboth))
 	     (if (eq (frame-parameter nil 'maximized) 'maximized)
 		 'maximized)
 	   'fullscreen)))))