A workaround to close currently opened menu. Send escape key if screen locker fails to grab input.

chrome/browser/chromeos/login/screen_locker.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/login/screen_locker.h"
 
 #include <string>
 #include <vector>
+#include <X11/extensions/XTest.h>
+#include <X11/keysym.h>
 
 #include "app/l10n_util.h"
+#include "app/x11_util.h"

[Daniel Erat, 2010/11/16 21:58:06]

still needs to be sorted

[oshima, 2010/11/17 01:00:43]

Done.

 #include "app/resource_bundle.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/message_loop.h"
 #include "base/singleton.h"
 #include "base/string_util.h"
 #include "base/timer.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/browser_thread.h"
@@ skipping 248 matching lines @@
         kbd_grab_status_(GDK_GRAB_INVALID_TIME),
         mouse_grab_status_(GDK_GRAB_INVALID_TIME) {
   }
 
   virtual void Show() {
     views::WidgetGtk::Show();
   }
 
   void ClearGrab() {
     GtkWidget* current_grab_window;
-    // Grab gtk input first so that the menu holding grab will close itself.
+    // Grab gtk input first so that the menu holding gtk grab will
+    // close itself.
     gtk_grab_add(window_contents());
 
-    // Make sure there is no grab widget so that gtk simply propagates
+    // Make sure there is no gtl grab widget so that gtk simply propagates

[Daniel Erat, 2010/11/16 21:58:06]

s/gtl/gtk/

[oshima, 2010/11/17 01:00:43]

Done.

     // an event.  This is necessary to allow message bubble and password
     // field, button to process events simultaneously. GTK
     // maintains grab widgets in a linked-list, so we need to remove
     // until it's empty.
     while ((current_grab_window = gtk_grab_get_current()) != NULL)
       gtk_grab_remove(current_grab_window);
+
+#if !defined(NDEBUG)
+    {
+      int event_base, error_base;
+      int major, minor;
+      // Make sure we have XTest extension.
+      DCHECK(XTestQueryExtension(x11_util::GetXDisplay(),
+                                 &event_base, &error_base,
+                                 &major, &minor));
+    }
+#endif
+
+    // The following code is an attempt to grab inputs by closing
+    // supposedly opened menu. This happens when a plugin has a menu
+    // opened.
+    if (kbd_grab_status_ == GDK_GRAB_ALREADY_GRABBED ||
+        kbd_grab_status_ == GDK_GRAB_FROZEN) {
+      // Send escape key if the keyboard is grabbed by other client.
+      Display* display = x11_util::GetXDisplay();

[Daniel Erat, 2010/11/16 21:58:06]

So the reason for adding a server grab around this code (and checking the
keyboard grab status again while you have the server grabbed) is that the grab
could've already been released at this point, in which case you'll send an event
to some other window.

+      KeyCode escape = XKeysymToKeycode(display, XK_Escape);  // escape
+      XTestFakeKeyEvent(display, escape, True, CurrentTime);
+      XTestFakeKeyEvent(display, escape, False, CurrentTime);
+      XFlush(display);
+    } else if (mouse_grab_status_ == GDK_GRAB_ALREADY_GRABBED ||

[Daniel Erat, 2010/11/16 21:58:06]

why 'else if' instead of keeping this as an independent if statement?

+        mouse_grab_status_ == GDK_GRAB_FROZEN) {

[Daniel Erat, 2010/11/16 21:58:06]

nit: indent this to line up with the mouse_grab_status_ on the previous line

+      // Successfully grabbed the keyboard, but pointer is still
+      // grabbed by other client. Another attempt to close supposedly
+      // opened menu by emulating keypress at the left top corner.
+      Display* display = x11_util::GetXDisplay();
+      Window root, child;
+      int root_x, root_y, win_x, winy;
+      unsigned int mask;
+      XQueryPointer(display,
+                    x11_util::GetX11WindowFromGtkWidget(window_contents()),
+                    &root, &child, &root_x, &root_y,
+                    &win_x, &winy, &mask);
+      XTestFakeMotionEvent(display, -1, -1, -1, CurrentTime);

[Daniel Erat, 2010/11/16 21:58:06]

I'm a bit nervous about (-1, -1) being used; there could be a window there. 
It'd be better if you used something farther offscreen.

[oshima, 2010/11/17 01:00:43]

changed to -10000, -10000

+      XTestFakeButtonEvent(display, 1, True, CurrentTime);
+      XTestFakeButtonEvent(display, 1, False, CurrentTime);
+      // Move the pointer back.
+      XTestFakeMotionEvent(display, -1, root_x, root_y, CurrentTime);
+      XFlush(display);
+    }
   }
 
   virtual gboolean OnButtonPress(GtkWidget* widget, GdkEventButton* event) {
     WidgetGtk::OnButtonPress(widget, event);
     // Never propagate event to parent.
     return true;
   }
 
   // Try to grab all inputs. It initiates another try if it fails to
   // grab and the retry count is within a limit, or fails with CHECK.
@@ skipping 626 matching lines @@
 
 bool ScreenLocker::AcceleratorPressed(const views::Accelerator& accelerator) {
   if (!background_view_->IsScreenSaverVisible()) {
     StartScreenSaver();
     return true;
   }
   return false;
 }
 
 }  // namespace chromeos