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diff --git a/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/hints/IHintStack.java b/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/hints/IHintStack.java
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index 000000000..16e3c42ea
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+++ b/bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/hints/IHintStack.java
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+/*******************************************************************************
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management
+ * in Industry THTH ry.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+/*
+ *
+ * @author Toni Kalajainen
+ */
+package org.simantics.utils.datastructures.hints;
+
+
+/**
+ * IHintStack is a layered stack of hint contexts.  
+ * Each hint context has a priority. 
+ * Hint set in higher priority context overrides all lower priority hints of 
+ * the same key.
+ * 
+ * Hint set in a hint context does not become effective if there 
+ * exists another hint of the same key in a higher priority context. 
+ * 
+ * If the higher priority context or its hint is removed, the next lower level hint
+ * becomes effective.
+ * 
+ * getHint() method is global. It returns the highest priority value for the key.
+ * It does not return the hint set for a specific context, instead it returns the hint
+ * set in the highest priority context.  
+ */
+public interface IHintStack extends IHintObservable {
+
+	void addHintContext(IHintContext hints, int priority);
+	
+	boolean removeHintContext(IHintContext hints);
+	
+	/**
+	 * Returns a wrapper hint context whose read operations originate from the stack, and
+	 * write operations to the a local stack (argument ctx)
+	 * 
+     * @param ctx the hint context to write into
+     * @return write-localized hint context based on this hint stack
+	 */
+	IHintContext createStackRead(final IHintContext ctx);	
+	
+}