Implementing the Mac "Quick Look" type of window

[Peter Haworth]

Not sure the correct term for this but I'm looking for a way to to  
implement windows that look like the "Quick Look" windows on a Mac.  
They "explode" out from the document icon popup menu that you select  
the Quick Look function  from.  They have a semi-transparent border  
around the document they display and a close button at the top left  
and a vertical scroll bar.

I thought maybe the opaque property of a card might be a starting  
point but it doesn't seem to affect the appearance of the card at  
all.  Also tried playing around with the various options of the  
Blending Properties but they seem to affect the appearance of objects  
on the card rather than the card itself.

Thanks for any pointers as to how to do this,

Pete Haworth