Index: umc/widgets/MultiSelect.js
===================================================================
--- umc/widgets/MultiSelect.js	(Revision 56310)
+++ umc/widgets/MultiSelect.js	(Arbeitskopie)
@@ -118,6 +118,13 @@
 			this._registerAtParentOnShowEvents(lang.hitch(this, 'resize'));
 		},
 
+		_setCustomValue: function() {
+			// overwrite handling of _SelectMixin
+			this.value = null; // force notification of watch handlers
+			this.set('value', this._initialValue);
+			this._resetValue = this._initialValue;
+		},
+
 		_getSizeAttr: function() {
 			return this.get('autoHeight');
 		},