Bug 101211 Generalize Type disables after cancelling Change Method Signature
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/ChangeTypeAction.java
fEditor= editor;
		setEnabled(SelectionConverter.getInputAsCompilationUnit(fEditor) != null);
	}
	/**
	 * Creates a new <code>ChangeTypeAction</code>. The action requires that
	 * the selection provided by the site's selection provider is of type
	 * <code>org.eclipse.jface.viewers.IStructuredSelection</code>.
	 * 
	 * @param site the site providing context information for this action
	 */
	public ChangeTypeAction(IWorkbenchSite site) {
		super(site);
		setText(RefactoringMessages.ChangeTypeAction_label); 
		setToolTipText(RefactoringMessages.ChangeTypeAction_tooltipText); 
		setDescription(RefactoringMessages.ChangeTypeAction_description); 
		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.CHANGE_TYPE_ACTION);
	}
	
	
	public void selectionChanged(IStructuredSelection selection) {
		try {
			setEnabled(RefactoringAvailabilityTester.isGeneralizeTypeAvailable(selection));
		} catch (JavaModelException e) {
			if (JavaModelUtil.isExceptionToBeLogged(e))
				JavaPlugin.log(e);
			setEnabled(false);
		}
	}
	public void run(IStructuredSelection selection) {
		try {