[gnome-shell] overviewControls: Use correct translation in dragBegin

[Florian Müllner <fmuellner src gnome org>]

commit 38c70e73b9e6a2e64533d5e2c48229e65a948ca5
Author: Florian Müllner <fmuellner gnome org>
Date:   Sun Aug 31 02:20:43 2014 +0200

    overviewControls: Use correct translation in dragBegin
    
    Commit 12845f0eefa reset translationX to 0 to fix the slide-in
    animation of the dash when dragging a search result, but 0 is the
    wrong value for the thumbnail slider - the next time it will be
    shown, it will just pop up instead of sliding in due to translationX
    already being at its target value.
    Fix this by making _updateTranslation take the actual visibility into
    account and call that to set the correct translation in dragBegin.

 js/ui/overviewControls.js |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/overviewControls.js b/js/ui/overviewControls.js
index 4bd3d67..02423f2 100644
--- a/js/ui/overviewControls.js
+++ b/js/ui/overviewControls.js
@@ -161,7 +161,8 @@ const SlidingControl = new Lang.Class({
         let translationEnd = 0;
         let translation = this._getTranslation();
 
-        if (this._visible) {
+        let shouldShow = (this._getSlide() > 0);
+        if (shouldShow) {
             translationStart = translation;
         } else {
             translationEnd = translation;
@@ -192,7 +193,7 @@ const SlidingControl = new Lang.Class({
 
     _onDragBegin: function() {
         this._inDrag = true;
-        this.layout.translationX = 0;
+        this._updateTranslation();
         this._updateSlide();
     },