That's an interesting idea. The issues you run into are that there is no way, as far as I know, to check for how the underlying window has been scrolled. If you can size the window and limit the found set so that no scrolling is possible (Easier, in most cases, for horizontal scrolling), then you might be able use Get (record number) to estimate the vertical position or a list or table-view layout.
Hmmmm.... Perhaps if you name all your fields with object names, you can do something like this following:
Set Variable [ $location; GetLayoutObjectAttribute ( Get ( ActiveLayoutObjectName ); "top" ) ]
New Window [ Height: $location + 50 ]
This will always add 50 pixels to where the top of the object is.
Nice idea if it's a script trigger popping up the window while the cursor is still in the field.
If the user clicks a button to trigger the pop-up, you'll get the position of the button instead of the field..
If the cursor is in the field at the point that the script is envoked whether it be by a button, custom menu, script trigger, manage scripts, etc it should work fine.
I stand corrected.