Add disable-mouse-button-modifiers message

Similar to the disable-keybindings message, Sugar would like to be able
to disable this specific part of the metacity functionality without
changing the GSettings configuration (which would also affect GNOME).

Add a new metacity-message command to disable mouse button modifiers,
which ordinarily let windows be dragged around the screen when a specific
modifier is pressed.

https://bugzilla.gnome.org/show_bug.cgi?id=677115

3 files changed, 56 insertions, 2 deletions

diff --git a/src/core/atomnames.h b/src/core/atomnames.h
index 338d0555..14dbd8f3 100644
--- a/src/core/atomnames.h
+++ b/src/core/atomnames.h
@@ -57,6 +57,7 @@ item(_KWM_WIN_ICON)
 item(_METACITY_RESTART_MESSAGE)    
 item(_METACITY_RELOAD_THEME_MESSAGE)
 item(_METACITY_SET_KEYBINDINGS_MESSAGE)
+item(_METACITY_SET_MOUSEMODS_MESSAGE)
 item(_METACITY_TOGGLE_VERBOSE)
 item(_GNOME_PANEL_ACTION)
 item(_GNOME_PANEL_ACTION_MAIN_MENU)
diff --git a/src/core/display.c b/src/core/display.c
index b70112d0..440f2fb8 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -135,6 +135,8 @@ typedef struct
  */
 static MetaDisplay *the_display = NULL;
 
+static gboolean mousemods_disabled = FALSE;
+
 #ifdef WITH_VERBOSE_MODE
 static void   meta_spew_event           (MetaDisplay    *display,
                                          XEvent         *event);
@@ -157,6 +159,9 @@ static void    process_selection_clear   (MetaDisplay   *display,
 
 static void    update_window_grab_modifiers (MetaDisplay *display);
 
+static void    set_mousemods_disabled (MetaDisplay *display,
+                                       gboolean     setting);
+
 static void    prefs_changed_callback    (MetaPreference pref,
                                           void          *data);
 
@@ -2271,6 +2276,13 @@ event_callback (XEvent   *event,
                   meta_set_keybindings_disabled (display, !event->xclient.data.l[0]);
                 }
               else if (event->xclient.message_type ==
+                       display->atom__METACITY_SET_MOUSEMODS_MESSAGE)
+                {
+                  meta_verbose ("Received set mousemods request = %d\n",
+                                (int) event->xclient.data.l[0]);
+                  set_mousemods_disabled (display, !event->xclient.data.l[0]);
+                }
+              else if (event->xclient.message_type ==
                        display->atom__METACITY_TOGGLE_VERBOSE)
                 {
                   meta_verbose ("Received toggle verbose message\n");
@@ -3701,7 +3713,7 @@ meta_display_grab_window_buttons (MetaDisplay *display,
    * XSync()
    */
 
-  if (display->window_grab_modifiers != 0)
+  if (display->window_grab_modifiers != 0 && !mousemods_disabled)
     {
       gboolean debug = g_getenv ("METACITY_DEBUG_BUTTON_GRABS") != NULL;
       int i;
@@ -3835,6 +3847,15 @@ meta_display_ungrab_focus_window_button (MetaDisplay *display,
   }
 }
 
+static void
+set_mousemods_disabled (MetaDisplay *display,
+                        gboolean     setting)
+{
+  mousemods_disabled = setting;
+  prefs_changed_callback(META_PREF_MOUSE_BUTTON_MODS, display);
+  meta_verbose ("Mouse button modifiers %s\n", mousemods_disabled ? "disabled" : "enabled");
+}
+
 void
 meta_display_increment_event_serial (MetaDisplay *display)
 {
diff --git a/src/tools/metacity-message.c b/src/tools/metacity-message.c
index 8d5548c3..9aae7331 100644
--- a/src/tools/metacity-message.c
+++ b/src/tools/metacity-message.c
@@ -114,6 +114,34 @@ send_set_keybindings (gboolean enabled)
   XSync (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), False);
 }
 
+static void
+send_set_mousemods (gboolean enabled)
+{
+  XEvent xev;
+
+  xev.xclient.type = ClientMessage;
+  xev.xclient.serial = 0;
+  xev.xclient.send_event = True;
+  xev.xclient.display = GDK_DISPLAY_XDISPLAY (gdk_display_get_default ());
+  xev.xclient.window = gdk_x11_get_default_root_xwindow ();
+  xev.xclient.message_type = XInternAtom (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()),
+                                          "_METACITY_SET_MOUSEMODS_MESSAGE",
+                                          False);
+  xev.xclient.format = 32;
+  xev.xclient.data.l[0] = enabled;
+  xev.xclient.data.l[1] = 0;
+  xev.xclient.data.l[2] = 0;
+
+  XSendEvent (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()),
+              gdk_x11_get_default_root_xwindow (),
+              False,
+	      SubstructureRedirectMask | SubstructureNotifyMask,
+	      &xev);
+
+  XFlush (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()));
+  XSync (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), False);
+}
+
 #ifdef WITH_VERBOSE_MODE
 static void
 send_toggle_verbose (void)
@@ -148,7 +176,7 @@ static void
 usage (void)
 {
   g_printerr (_("Usage: %s\n"),
-              "metacity-message (restart|reload-theme|enable-keybindings|disable-keybindings|toggle-verbose)");
+              "metacity-message (restart|reload-theme|enable-keybindings|disable-keybindings|enable-mouse-button-modifiers|disable-mouse-button-modifiers|toggle-verbose)");
   exit (1);
 }
 
@@ -170,6 +198,10 @@ main (int argc, char **argv)
     send_set_keybindings (TRUE);
   else if (strcmp (argv[1], "disable-keybindings") == 0)
     send_set_keybindings (FALSE);
+  else if (strcmp (argv[1], "enable-mouse-button-modifiers") == 0)
+    send_set_mousemods (TRUE);
+  else if (strcmp (argv[1], "disable-mouse-button-modifiers") == 0)
+    send_set_mousemods (FALSE);
   else if (strcmp (argv[1], "toggle-verbose") == 0)
     {
 #ifndef WITH_VERBOSE_MODE