Find/Replace Overlay: add help context to Overlay

Add the find/replace help context to the overlay which was also used for
the find/replace dialog. In particular, display help for find/replace
with regex patterns.

fixes #1994

bundles/org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/internal/findandreplace/overlay/FindReplaceOverlay.java

@@ -64,6 +64,7 @@
 import org.eclipse.ui.internal.findandreplace.SearchOptions;
 import org.eclipse.ui.internal.findandreplace.status.IFindReplaceStatus;
 
+import org.eclipse.ui.texteditor.IAbstractTextEditorHelpContextIds;
 import org.eclipse.ui.texteditor.StatusTextEditor;
 
 /**
@@ -428,6 +429,9 @@ private void bindListeners() {
 
 	@Override
 	public Control createContents(Composite parent) {
+		PlatformUI.getWorkbench().getHelpSystem().setHelp(getShell(),
+				IAbstractTextEditorHelpContextIds.FIND_REPLACE_DIALOG);
+
 		backgroundToUse = new Color(getShell().getDisplay(), new RGBA(0, 0, 0, 0));
 		Control ret = createDialog(parent);