Pick up dynamic changes in screen size (although some other things still cache them per-window). b=256646 r+sr=roc

widget/src/gtk2/nsScreenGtk.cpp

@@ -38,13 +38,45 @@
 
 #include "nsScreenGtk.h"
 
-#include <gdk/gdk.h>
 #include <gdk/gdkx.h>
 #include <gtk/gtk.h>
 #include <X11/Xatom.h>
 
+static GdkFilterReturn
+net_workarea_changed_filter(GdkXEvent *aGdkXEvent, GdkEvent *aGdkEvent,
+                            gpointer aClosure)
+{
+  XEvent *xevent = NS_STATIC_CAST(XEvent*, aGdkXEvent);
+  nsScreenGtk *ourScreen = NS_STATIC_CAST(nsScreenGtk*, aClosure);
+
+  switch (xevent->type) {
+    case PropertyNotify:
+      {
+        XPropertyEvent *propertyEvent = &xevent->xproperty;
+        if (propertyEvent->atom == ourScreen->NetWorkareaAtom()) {
+          ourScreen->Init(PR_TRUE);
+        }
+      }
+      break;
+    default:
+      break;
+  }
+
+  return GDK_FILTER_CONTINUE;
+}
+
+static void
+screen_size_changed_cb(GdkScreen *aScreen, gpointer aClosure)
+{
+  nsScreenGtk *ourScreen = NS_STATIC_CAST(nsScreenGtk*, aClosure);
+  ourScreen->Init(PR_TRUE);
+}
+
+
 nsScreenGtk :: nsScreenGtk (  )
-  : mScreenNum(0),
+  : mScreen(nsnull),
+    mRootWindow(nsnull),
+    mScreenNum(0),
     mRect(0, 0, 0, 0),
     mAvailRect(0, 0, 0, 0)
 {
@@ -53,6 +85,16 @@ nsScreenGtk :: nsScreenGtk (  )
 
 nsScreenGtk :: ~nsScreenGtk()
 {
+  if (mRootWindow) {
+    gdk_window_remove_filter(mRootWindow, net_workarea_changed_filter, this);
+    g_object_unref(mRootWindow);
+    mRootWindow = nsnull;
+  }
+  if (mScreen) {
+    g_signal_handler_disconnect(G_OBJECT(mScreen), mSizeChangedHandler);
+    g_object_unref(mScreen);
+    mScreen = nsnull;
+  }
 }
 
 
@@ -106,25 +148,49 @@ nsScreenGtk :: GetColorDepth(PRInt32 *aColorDepth)
 
 
 void
-nsScreenGtk :: Init ()
+nsScreenGtk :: Init (PRBool aReInit)
 {
-  mAvailRect = mRect = nsRect(0, 0, gdk_screen_width(), gdk_screen_height());
+  if (!aReInit) {
+    // Listen for "size_changed" signals on default screen to pick up
+    // changes.  The problem with this (event with _after) is that
+    // toolbars haven't been resized yet when we get this, so instead of
+    // excluding toolbars known by the window manager, we get a bunch of
+    // NS_WARNING("Invalid bounds") below.
+    mScreen = gdk_screen_get_default();
+    g_object_ref(mScreen);
+
+    mSizeChangedHandler =
+      g_signal_connect_after(G_OBJECT(mScreen), "size_changed",
+                             G_CALLBACK(screen_size_changed_cb), this);
+  }
+
+  mAvailRect = mRect = nsRect(0, 0, gdk_screen_get_width(mScreen),
+                              gdk_screen_get_height(mScreen));
+
 
   // We need to account for the taskbar, etc in the available rect.
   // See http://freedesktop.org/Standards/wm-spec/index.html#id2767771
 
-  // XXX It doesn't change that often, but we should probably
-  // listen for changes to _NET_WORKAREA.
   // XXX do we care about _NET_WM_STRUT_PARTIAL?  That will
   // add much more complexity to the code here (our screen
   // could have a non-rectangular shape), but should
   // lead to greater accuracy.
 
+  if (!aReInit) {
 #if GTK_CHECK_VERSION(2,2,0)
-  GdkWindow *root_window = gdk_get_default_root_window();
+    mRootWindow = gdk_get_default_root_window();
 #else
-  GdkWindow *root_window = GDK_ROOT_PARENT();
+    mRootWindow = GDK_ROOT_PARENT();
 #endif // GTK_CHECK_VERSION(2,2,0)
+    g_object_ref(mRootWindow);
+
+    gdk_window_set_events(mRootWindow,
+                          GdkEventMask(gdk_window_get_events(mRootWindow) |
+                                       GDK_PROPERTY_CHANGE_MASK));
+    gdk_window_add_filter(mRootWindow, net_workarea_changed_filter, this);
+    mNetWorkareaAtom =
+      XInternAtom(GDK_WINDOW_XDISPLAY(mRootWindow), "_NET_WORKAREA", False);
+  }
 
   long *workareas;
   GdkAtom type_returned;
@@ -140,7 +206,7 @@ nsScreenGtk :: Init ()
   gdk_error_trap_push();
 
   // gdk_property_get uses (length + 3) / 4, hence G_MAXLONG - 3 here.
-  if (!gdk_property_get(root_window,
+  if (!gdk_property_get(mRootWindow,
                         gdk_atom_intern ("_NET_WORKAREA", FALSE),
                         cardinal_atom,
                         0, G_MAXLONG - 3, FALSE,

widget/src/gtk2/nsScreenGtk.h

@@ -40,9 +40,10 @@
 
 #include "nsIScreen.h"
 #include "nsRect.h"
+#include "gdk/gdk.h"
+#include <X11/Xlib.h>
 
 #ifdef MOZ_ENABLE_XINERAMA
-#include <X11/Xlib.h>
 #include <X11/extensions/Xinerama.h>
 #endif // MOZ_ENABLE_XINERAMA
 
@@ -57,13 +58,19 @@ public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSISCREEN
 
-  void Init();
+  void Init(PRBool aReInit = PR_FALSE);
 #ifdef MOZ_ENABLE_XINERAMA
   void Init(XineramaScreenInfo *aScreenInfo);
 #endif
 
+  Atom NetWorkareaAtom() { return mNetWorkareaAtom; }
+
 private:
+  GdkScreen *mScreen;
+  GdkWindow *mRootWindow;
   PRUint32 mScreenNum;
+  gulong mSizeChangedHandler;
+  Atom mNetWorkareaAtom;
   nsRect mRect; // in pixels, not twips
   nsRect mAvailRect; // in pixels, not twips
 };