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
Martin Carlberg
daboe01
jasperdeb
Alexandre Wilhelm