Fix bug which caused duplicate applet orders when dropping them in the same position.

Author: samw-26

js/ui/panel.js

@@ -1970,7 +1970,12 @@ PanelZoneDNDHandler.prototype = {
 
         let children = this._panelZone.get_children();
         let curAppletPos = 0;
-        let insertAppletPos = 0;
+        let insertAppletPos = -1;
+
+        const {
+            panel: { panelId: sourceAppletPanel },
+            locationLabel: sourceAppletLocation,
+        } = source.actor._applet;
 
         for (let i = 0, len = children.length; i < len; i++) {
             if (children[i]._delegate instanceof Applet.Applet){
@@ -1982,7 +1987,12 @@ PanelZoneDNDHandler.prototype = {
             }
         }
 
-        source.actor._applet._newOrder = insertAppletPos;
+        const isSameLocation = (
+            sourceAppletPanel === this._panelId
+            && sourceAppletLocation === this._zoneString
+            && insertAppletPos === -1
+        );
+        if (!isSameLocation) source.actor._applet._newOrder = insertAppletPos === -1 ? 0 : insertAppletPos;
         source.actor._applet._newPanelLocation = this._panelZone;
         source.actor._applet._zoneString = this._zoneString;
         source.actor._applet._newPanelId = this._panelId;