[gnome-shell] workspaceThumbnail: avoid bouncing of the drop placeholder above the first workspace

[Owen Taylor <otaylor src gnome org>]

commit c63fe5ee240791156bf4693ac5b2a79725b4cc9b
Author: Stefano Facchini <stefano facchini gmail com>
Date:   Wed Nov 23 11:00:30 2011 +0100

    workspaceThumbnail: avoid bouncing of the drop placeholder above the first workspace
    
    https://bugzilla.gnome.org/show_bug.cgi?id=664622

 js/ui/workspaceThumbnail.js |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/workspaceThumbnail.js b/js/ui/workspaceThumbnail.js
index 6b1dc80..52b2a74 100644
--- a/js/ui/workspaceThumbnail.js
+++ b/js/ui/workspaceThumbnail.js
@@ -611,7 +611,11 @@ const ThumbnailsBox = new Lang.Class({
         let thumbHeight = this._porthole.height * this._scale;
 
         let workspace = -1;
-        let firstThumbY = this._thumbnails[0].actor.y;
+        let firstThumbY;
+        if (this._dropPlaceholderPos == 0)
+            firstThumbY = this._dropPlaceholder.y;
+        else
+            firstThumbY = this._thumbnails[0].actor.y;
         for (let i = 0; i < this._thumbnails.length; i ++) {
             let targetBase = firstThumbY + (thumbHeight + spacing) * i;