[plt-scheme] MrEd container

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Fri Jun 15 18:16:11 EDT 2007

At Fri, 15 Jun 2007 09:44:50 +0200 (CEST), Ivanyi Peter wrote:
> While I am revising the MrEd Designer I came across a
> problem which
> I would like to solve. I would like to have a new type of
> container which
> can include any of the already implemented widgets. However the
> container widget is, lets say, one pixel wider and higher
> than the 
> contained widget and if the user clicks on the contained
> widget then 
> the container draws a line around the contained widget. 
> I found no real good example for it.
> I suspect I have to subclass a canvas% with an interface of 
> area-container<%>. Is that right? 
> I also have to deal with events but I think I can solve that
> part.
> Can someone help me with this?

This sounds to me like a variant of panel%.

Implementing the border is a bit tricky, though, since you can't draw
directly on a panel. But you could have four skinny canvases around a
nested panel.


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