[gnome-shell] Add a comment about the use of the transparent background and set its opacity to 0

[Colin Walters <walters src gnome org>]

commit 587f04f80760ac6999fae9b81398e820846c89a2
Author: Marina Zhurakhinskaya <marinaz redhat com>
Date:   Thu Jun 25 14:33:24 2009 -0400

    Add a comment about the use of the transparent background and set its opacity to 0
    
    Add a comment about the use of the transparent background to catch clicks
    in the workspaces area when the dash panes are being displayed and dismiss
    the dash panes.
    
    Set opacity for the background to 0 instead of using a transparent background
    color so that Clutter optimizes the drawing of the background actor.

 js/ui/overlay.js |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/overlay.js b/js/ui/overlay.js
index 64089ce..628a20a 100644
--- a/js/ui/overlay.js
+++ b/js/ui/overlay.js
@@ -798,7 +798,10 @@ Overlay.prototype = {
         background.y = -global.screen_height * (4 * BACKGROUND_SCALE - 3) / 6;
         this._group.add_actor(background);
 
-        this._transparentBackground = new Clutter.Rectangle({ color: TRANSPARENT_COLOR,
+        // Transparent background is used to catch clicks outside of the dash panes when the panes
+        // are being displayed and the workspaces area should not be reactive. Catching such a
+        // click results in the panes being closed and the workspaces area becoming reactive again. 
+        this._transparentBackground = new Clutter.Rectangle({ opacity: 0,
                                                               width: global.screen_width,
                                                               height: global.screen_height - Panel.PANEL_HEIGHT,
                                                               y: Panel.PANEL_HEIGHT,