Cmd -Z in a standalone

[Ron]

Greetings,

More menu madness. I assigned cmd-Z as the keyboard equivalent to 'close all
windows'. Built a standalone. Tried cmd-Z and nothing happened. But I
selected text, deleted it and pressed cmd-Z. The deleted text reappears.
Alternately appearing/disappearing with each press of cmd-Z, just like an
undo/redo feature. 

Is this a feature? bug?

OS 9.2.2 and 1.1.1

thanks
Ron