Mysterious popup stack behavior

[David Epstein]

Does anyone understand how Metacard handles the size, positioning, and
scrolling behavior of stacks when they are shown using a Popup command?  For
example:

-- the objects in a popped up stack scroll up or down under circumstances
that I cannot quite specify.  It seems to happen when Metacard thinks the
stack too tall for the screen, so it truncates a bit of the image and leaves
a gray area that, when a depressed mouse enters it, causes the stack's
objects to scroll.

-- if I set the height of a stack, and then open it with a popup command,
Metacard sometimes changes that height.  This certainly happens when the
height exceeds the screen's height, but also happens in other cases.  The
"maximum height" and "minimum height" properties also get adjusted.

These behaviors may well be useful, but I need to know what to expect.  I
would like to pop up a panel whose position and height I can specify and
whose controls will not scroll.  Is there some height range within which I
can do this?

Many thanks.

David Epstein