Bug 84533 Refactoring does not do anything...
Build: I-20050202 1. Create a new Hello world plugin project. Call it 'com.example.xyz' and accept all defaults. 2. Close the manifest editor for the newly created plugin.xml to take PDE out of the equation. 3. Open the plugin.xml in a plain text editor. 4. Right-click on the 'com.example.xyz' project and choose to rename it to 'com.example.xyz.bla' with textual matches in plugin.xml files. 5. In the preview, uncheck the 'plugin.xml - com.example.xyz). All its children are now unchecked 6. Check the second match in the plugin.xml file only (ie. the one for the 'class' attribute. 7. click OK. NOTHING HAPPENS!
org.eclipse.ltk.core.refactoring/src/org/eclipse/ltk/core/refactoring/Change.java
* This method is also called by the {@link IUndoManager UndoManager} to decide if
	 * an undo or redo change is still valid and therefore can be executed.
	 * </p>
	 * 
	 * @param pm a progress monitor.
	 * 
	 * @return a refactoring status describing the outcome of the validation check
	 * 
	 * @throws CoreException if an error occurred during validation check. The change
	 *  is to be treated as invalid if an exception occurs
	 * 
	 * @throws OperationCanceledException if the validation check got cancelled
	 */
	public abstract RefactoringStatus isValid(IProgressMonitor pm) throws CoreException, OperationCanceledException;
	
	/**
	 * Performs this change. If this method is call on an invalid or disabled change 
	 * object the result is unspecified. Changes should in general not respond to
	 * {@link IProgressMonitor#isCanceled()} since canceling a change tree in the
	 * middle of its execution leaves the workspace in a half changed state.   
	 * 
	 * @param pm a progress monitor
	 * 
	 * @return the undo change for this change object or <code>null</code> if no
	 *  undo is provided
	 * 
	 * @throws CoreException if an error occurred during change execution
	 */
	public abstract Change perform(IProgressMonitor pm) throws CoreException;