keybindings: Grab buttons with any modifier combo on unfocused windows

We currently only focus unfocused windows on button press if no
modifiers (or just ignored modifiers) are in effect. This behavior
seems surprising and counter-intuitive so let's do it for any modifier
combination instead.

https://bugzilla.gnome.org/show_bug.cgi?id=746642

src/core/window.c

@@ -4816,7 +4816,12 @@ meta_window_set_focused_internal (MetaWindow *window,
        */
       if (meta_prefs_get_focus_mode () == G_DESKTOP_FOCUS_MODE_CLICK ||
           !meta_prefs_get_raise_on_click())
-        meta_display_ungrab_focus_window_button (window->display, window);
+        {
+          meta_display_ungrab_focus_window_button (window->display, window);
+          /* Since we ungrab with XIAnyModifier above, all button
+             grabs go way so we need to re-grab the window buttons. */
+          meta_display_grab_window_buttons (window->display, window->xwindow);
+        }
 
       g_signal_emit (window, window_signals[FOCUS], 0);