Bug 89020 [Undo] Operation throws assertion failure if undo limit is set to 0
I20050324-0800 Unfortunately existing clients of text's undo manager were allowed to set any number without failing. This is no longer possible: an assertion failure occurrs if the limit is smaller than 1. I will add code on my side that will handle the negative numbers but the operation history must allow 0.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
* listeners to receive notifications before and after the execution of the
	 * operation. Listeners will be notified before (
	 * <code>ABOUT_TO_EXECUTE</code>) and after (<code>DONE</code> or
	 * <code>OPERATION_NOT_OK</code>).
	 * 
	 * If the operation successfully executes, an additional notification that
	 * the operation has been added to the history (<code>OPERATION_ADDED</code>)
	 * will be sent.
	 * 
	 * @param operation -
	 *            the operation to be executed and then added to the history
	 * 
	 * @param monitor -
	 *            the progress monitor to be used (or <code>null</code>)
	 *            during the operation.
	 * 
	 * @param info -
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller containing additional information. When this API is
	 *            called from the UI, callers can use this to provide additional
	 *            info for prompting the user. If an IAdaptable is provided,
	 *            callers are encouraged to provide an adapter for the
	 *            org.eclipse.swt.widgets.Shell.class.
	 * 
	 * @return the IStatus indicating whether the execution succeeded.
	 * 
	 * The severity code in the returned status describes whether the operation
	 * succeeded and whether it was added to the history. <code>OK</code>
	 * severity indicates that the execute operation was successful and that the
	 * operation has been added to the history. Listeners will receive the