[gnome-boxes] machine: Correct thumbnail for under construction box

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 07c669b178767e2589ed369930940e2a59b40cc5
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Tue Mar 4 00:36:20 2014 +0000

    machine: Correct thumbnail for under construction box
    
    In commit 2526a28, we lost the code to use 'media-optical' icon as
    thumbnail for an under construction box. This patch brings back the
    (unintentionally) removed code.

 src/machine.vala |   20 ++++++++++++++++++--
 1 files changed, 18 insertions(+), 2 deletions(-)
---
diff --git a/src/machine.vala b/src/machine.vala
index 415b563..a444f42 100644
--- a/src/machine.vala
+++ b/src/machine.vala
@@ -513,8 +513,24 @@ private abstract class Boxes.Machine: Boxes.CollectionItem, Boxes.IPropertiesPro
 
             break;
         case UIState.PROPERTIES:
-            if (pixbuf != null)
-                App.window.sidebar.screenshot.set_from_pixbuf (pixbuf);
+            Gdk.Pixbuf pixbuf = null;
+            if (previous_ui_state == UIState.WIZARD) {
+                var theme = Gtk.IconTheme.get_for_screen (App.window.get_screen ());
+                pixbuf = new Gdk.Pixbuf (Gdk.Colorspace.RGB, true, 8,
+                                         Machine.SCREENSHOT_WIDTH, Machine.SCREENSHOT_HEIGHT);
+                pixbuf.fill (0x00000000); // Transparent
+                try {
+                    var icon = theme.load_icon ("media-optical", Machine.SCREENSHOT_HEIGHT, 0);
+                    // Center icon in pixbuf
+                    icon.copy_area (0, 0, Machine.SCREENSHOT_HEIGHT, Machine.SCREENSHOT_HEIGHT, pixbuf,
+                                    (Machine.SCREENSHOT_WIDTH - Machine.SCREENSHOT_HEIGHT) / 2, 0);
+                } catch (GLib.Error err) {
+                    warning (err.message);
+                }
+            } else {
+                pixbuf = this.pixbuf;
+            }
+            App.window.sidebar.screenshot.set_from_pixbuf (pixbuf);
 
             break;
         }