defer setting the auto refresh until after the channel viewer has been rendered

pyweb/mumble/media/js/channelviewer.js

@@ -154,9 +154,11 @@ Ext.ux.MumbleChannelViewer = function( config ){
     });
 
     this.autoRefreshId = 0;
-    this.setAutoRefresh();
-    if( this.refreshInterval == 0 )
-        this.refresh();
+    this.on("afterrender", function(){
+        this.setAutoRefresh();
+        if( this.refreshInterval == 0 )
+            this.refresh();
+    }, this);
 }
 
 Ext.extend( Ext.ux.MumbleChannelViewer, Ext.tree.TreePanel, {