Bug 89031 [Undo/Redo] IWorkbench#getOperationSupport() marked experimental
IWorkbench#getOperationSupport() marked experimental
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
/**
	 * <p>
	 * Open this composite operation and consider it an operation that contains
	 * other related operations. Consider all operations that are subsequently
	 * executed or added to be part of this operation. When an
	 * operation is opened, listeners will immediately receive a notification
	 * depending on the mode in which the operation is opened. (<code>ABOUT_TO_EXECUTE</code>,
	 * <code>ABOUT_TO_UNDO</code>, <code>ABOUT_TO_REDO</code>) for the
	 * opened operation. Notifications for any other execute or add
	 * while this operation is open will not occur. Instead, those operations
	 * will be added to the current operation.
	 * 
	 * <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 history
	 * as the triggering undo operation. When an operation is open, any
	 * subsequent requests to execute, add, undo, or redo another operation will
	 * result in that operation being added to the open operation. Once the
	 * operation is closed, the composite will be considered an atomic
	 * operation.
	 * 
	 * <p>
	 * When a composite is open, operations that are added to the history will
	 * be considered part of the open operation instead. Operations that are
	 * executed while a composite is open will first be executed and then added
	 * to the composite.
	 * 
	 * <p>
	 * Open operations cannot be nested. If this method is called when another
	 * operation is open, that operation will be closed first.