-- card: 10998 from stack: in.0
-- bmap block id: 0
-- flags: 0000
-- background id: 3797
-- name: 


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Date: 	  Mon, 14 Dec 87 21:03:25 PST
From: PUGH@NMFECC.ARPA


Well, I may have the first instance of Undo in a Hypercard stack.  This just 
came to me and I wonder why I haven't heard of it in any other stacks.

on doMenu x
  if x is "Undo" then
    global changedStuff, whatChanged
    put whatChanged into temp
    put changedStuff into whatChanged
    put temp into changedStuff
  else
    pass doMenu
  end if
end doMenu

And in a button or other script somewhere :

global changedStuff, whatChanged
put the name of ??? into whatChanged
put whatChanged into changedStuff
put ??? into whatchanged
...

You get the idea, I assume...

By using some global variables and placing this in your stack script, you can 
implement Undo with the best of them.  Set some condition under which you can 
Undo, and you can call Hypercard if you can't Undo.  It's great!  

I just thought I should remind everyone that just cause it's Hypercard doesn't
mean it has to be unstandard! 



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Undo Your Stacks!