Bug 67168 Change Signature shows error message twice [refactoring]
200406111814 public class TestClass { void change() { } x } Try to 'Change Method Signature' on 'change()'. The error message dialog always shows up twice.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/ModifyParametersAction.java
}
	
	/**
	 * Note: This method is for internal use only. Clients should not call this method.
	 */
	public void selectionChanged(JavaTextSelection selection) {
		try {
			setEnabled(canEnable(selection));
		} catch (JavaModelException e) {
			setEnabled(false);
		}
	}
	
	private boolean canEnable(JavaTextSelection selection) throws JavaModelException {
		
		IJavaElement[] elements= selection.resolveElementAtOffset(); 
		if (elements.length > 1)
			return false;
		if (elements.length == 1 && (elements[0] instanceof IMethod))
			return ChangeSignatureRefactoring.isAvailable((IMethod)elements[0]);
		
		IJavaElement elementAt= selection.resolveEnclosingElement();
		return (elementAt instanceof IMethod) && ChangeSignatureRefactoring.isAvailable((IMethod)elementAt);
	}
	
	/*
	 * @see SelectionDispatchAction#run(IStructuredSelection)
	 */
	public void run(IStructuredSelection selection) {
		try {