fix for cal preselection of an existing event

tracim/tracim/public/_caldavzap/forms.js

 			$('#event_details_template').find('svg[data-type="select_icon"]').replaceWith($('<div>').append($(newSVG).clone()).html());
 		}
 		/*************************** END OF BAD HACKS SECTION ***************************/
-		if(calEvent.etag!='')
-			$('#event_calendar').val(calEvent.res_id);
+		if(calEvent.etag!='') {
+      window.setTimeout(function () {
+        $('#event_calendar').val(calEvent.res_id);
+      }, 1)
+    }
 	}
 
 	if(repeatOne=='editOnly' || $('#recurrenceID').val()!='')