diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/FolderInfo.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/FolderInfo.java
index 11265d0fc35..9d5134de5ea 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/FolderInfo.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/FolderInfo.java
@@ -996,12 +996,28 @@ public class FolderInfo extends ResourceInfo implements IFolderInfo {
 	
 	private ITool[] calculateToolsArray(ITool[] removed, ITool[] added){
 		ITool tools[] = getTools();
-		HashSet set = new HashSet();
-		set.addAll(Arrays.asList(tools));
-		set.removeAll(Arrays.asList(removed));
-		set.addAll(Arrays.asList(added));
+		Map map = calcExtToolIdToToolMap(tools);
+		Map removedMap = calcExtToolIdToToolMap(removed);
+		for(Iterator iter = removedMap.keySet().iterator(); iter.hasNext();){
+			map.remove(iter.next());
+		}
+		map.putAll(calcExtToolIdToToolMap(added));
 		
-		return (ITool[])set.toArray(new ITool[set.size()]);
+		return (ITool[])map.values().toArray(new ITool[map.size()]);
+	}
+	
+	private Map calcExtToolIdToToolMap(ITool tools[]){
+		Map map = new HashMap();
+		for(int i = 0; i < tools.length; i++){
+			ITool tool = tools[i];
+			ITool extTool = ManagedBuildManager.getExtensionTool(tool);
+			if(extTool == null)
+				extTool = tool;
+			
+			map.put(extTool.getId(), tool);
+		}
+		
+		return map;
 	}
 	
 	private ITool[][] calculateConflictingTools(ITool[] newTools){
diff --git a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/ToolSelectionDialog.java b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/ToolSelectionDialog.java
index 725c58dedc8..4514819983b 100644
--- a/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/ToolSelectionDialog.java
+++ b/build/org.eclipse.cdt.managedbuilder.ui/src/org/eclipse/cdt/managedbuilder/ui/properties/ToolSelectionDialog.java
@@ -182,13 +182,14 @@ public class ToolSelectionDialog extends Dialog {
 			if (!exists) added.add(t);
 			add(t, t2, !exists);
 		}
-		if (check && removed.size() > 0 || added.size() > 0) {
+		if (true/*check && removed.size() > 0 || added.size() > 0 */) {
 			IModificationStatus st = fi.getToolChainModificationStatus(
 					(ITool[])removed.toArray(new ITool[removed.size()]), 
 					(ITool[])added.toArray(new ITool[added.size()]));
 			if (st.isOK()) {
 				errorLabel.setText("");  //$NON-NLS-1$
-				getButton(IDialogConstants.OK_ID).setEnabled(true);
+				if(getButton(IDialogConstants.OK_ID) != null)
+					getButton(IDialogConstants.OK_ID).setEnabled(true);
 			} else {
 				int c = st.getCode();
 				String s = "";  //$NON-NLS-1$