Bug 88352 Operation supports leaks contexts via action handler
I20050315-1100 Susan, this is a different leak from the one that I reported. Test Case: 1. open text editor 2. close text editor ==> DefaultUndoManager is leaked due to undo/redo actions handlers still holding on to the context.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
* @param context -
	 *            the context for the undo
	 * @return the array of operations in the history
	 */
	IUndoableOperation[] getUndoHistory(IUndoContext context);
	/**
	 * <p>
	 * Open this operation and consider it the primary operation in a batch of
	 * related operations. Consider all operations that are subsequently
	 * executed (or added) to be part of this operation and assign the
	 * context(s) of subsequent operations to this operation. When an operation
	 * is opened, listeners will immediately receive an
	 * <code>ABOUT_TO_EXECUTE</code>) notification for the operation.
	 * Notifications for execution or adding subsequent operations will not be
	 * sent as long as this operation is open.
	 * 
	 * <p>
	 * Note: This method is intended to be used by legacy undo frameworks that
	 * do not expect related undo operations to appear in the same undo stack as
	 * the triggering undo operation. When an operation is open, any subsequent
	 * operations added or executed are assumed to be triggered by model change
	 * events caused by the originating operation. Therefore, they will not be
	 * considered as independent operations and will not be added to the
	 * operation history. Instead, their contexts will be added to the open
	 * operation and they will be disposed. Once the operation is closed,
	 * requests to undo or redo it will result in only the originating (primary)
	 * operation being undone or redone. The assumption is that the undos
	 * corresponding to the original operation will be triggered by model change
	 * notifications similar to those that triggered the original operations.
	 *