Fix calendar date picker in sidebox stops resizing after switching between tabs

calendar/js/app.js

@@ -3465,11 +3465,12 @@ app.classes.calendar = (function(){ "use strict"; return AppJS.extend(
 		{
 			window.clearInterval(nm._autorefresh_timer);
 		}
+		var self = this;
 		var refresh = function() {
 			// Deleted events are not coming properly, so clear it all
-			this._clear_cache();
+			self._clear_cache();
 			// Force redraw to current state
-			this.setState({state: this.state});
+			self.setState({state: self.state});
 
 			// This is a fast update, but misses deleted events
 			//app.calendar._fetch_data(app.calendar.state);