Bug 162655 [Undo] [IDE] - Undoing a delete should check for existence of resources to be restored
N20061027. - I deleted two projects (along with their content). I read the warning that undo delete cannot restore the content and said "OK." - Then I checked out those same projects from HEAD. - Then I selected "Undo Delete Resources." This overwrote my code with empty projects. I think that "Undo Delete Resources" should become invalid if the resources exist again, because you'll end up replacing content without keeping a backup.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/AbstractResourcesOperation.java
/**
	 * Create an Abstract Resources Operation
	 * 
	 * @param resourceDescriptions
	 *            the resourceDescriptions describing resources to be created
	 * @param label
	 *            the label of the operation
	 */
	AbstractResourcesOperation(ResourceDescription[] resourceDescriptions,
			String label) {
		super(label);
		addContext(WorkspaceUndoUtil.getWorkspaceUndoContext());
		setResourceDescriptions(resourceDescriptions);
	}
	/**
	 * Delete any resources known by this operation. Store enough information to
	 * undo and redo the operation.
	 * 
	 * @param monitor
	 *            the progress monitor to use for the operation
	 * @param uiInfo
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller in order to supply UI information for prompting the
	 *            user if necessary. When this parameter is not
	 *            <code>null</code>, it contains an adapter for the
	 *            org.eclipse.swt.widgets.Shell.class
	 * @param deleteContent
	 *            <code>true</code> if the content of any known projects
	 *            should be deleted along with the project. <code>false</code>
	 *            if project content should not be deleted.