--- /dev/null
+/*******************************************************************************\r
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
+ * in Industry THTH ry.\r
+ * All rights reserved. This program and the accompanying materials\r
+ * are made available under the terms of the Eclipse Public License v1.0\r
+ * which accompanies this distribution, and is available at\r
+ * http://www.eclipse.org/legal/epl-v10.html\r
+ *\r
+ * Contributors:\r
+ * VTT Technical Research Centre of Finland - initial API and implementation\r
+ *******************************************************************************/\r
+package org.simantics.browsing.ui.common.internal;\r
+\r
+\r
+/**\r
+ * An abstract reference to a single concrete graph explorer control item.\r
+ * \r
+ * @author Tuukka Lehtonen\r
+ */\r
+public interface UIElementReference {\r
+\r
+ /**\r
+ * @return <code>true</code> if this TreeReference actually contains an\r
+ * element behind it.\r
+ */\r
+ public boolean hasReference();\r
+\r
+ /**\r
+ * @return <code>false</code> only if {@link #hasReference()} returns true\r
+ * and the referenced control item not disposed. Note that\r
+ * this method must return <code>true</code> if\r
+ * {@link #hasReference()} returns <code>false</code>.\r
+ */\r
+ public boolean isDisposed();\r
+\r
+}\r