A text view handled undo: and redo: and registered its changes even when allowsUndo was NO, so Edit > Undo stayed enabled and did nothing.
Behaviour now follows canonical Cocoa: a text view that does not allow undo registers nothing and passes undo: and redo: on to the window, and Undo and Redo are enabled only when there is a change to undo or redo.
* CPTextView/CPTextView.j: Register changes only when undo is allowed, stop responding to undo: and redo: when it is not, and validate the Undo and Redo items against the undo manager.
* CPWindow/CPWindow.j: Validate the Undo and Redo items against the window's undo manager.
* Tests/AppKit/CPTextViewTest.j: Add tests for responding to undo:, registering changes and validating the Undo item.
* Tests/Manual/TextEditor/DocumentWindowController.j: Add toggleAllowsUndo: and validateMenuItem:, so that undo can be turned on and off for the active document.
* Tests/Manual/TextEditor/Resources/MainMenu.xib, Resources/MainMenu.cib: Add Edit > Allow Undo.
* Tests/Manual/TextEditor/WORKLIST.md: Remove the entry for this gap, record Allow Undo as tested, and add the key equivalent behaviour of disabled menu items for discussion.
David Richardson
66ea130c8d