Can cards in a stack be of different sizes

[Kurt Kaufman]

"...What you show above is just 'change the size of the stack window as 
we go
along'. So yes, you can fake it but the stack has to be resized by
scripting, right?..."

This brings up an interesting thought:  To what extent are Rev's 
objects created, sized, etc. at runtime?  For that matter, aren't they 
actually instructions handed off to the operating system, anyway (as 
opposed to, say, something like HyperCard's field scrollbars which I 
understand to have been "internal", i.e. not using the operating 
system's built-in resources).

-Kurt