Why not keep the current selection method, and replace the old Scrolling capture with the New And Improved! Scrolling capture? Should leave any previous workflow the same, imho.
Yeah i guess that's mostly what i was suggesting.. The only change would be like so:
OLD METHOD:
Trigger an object/scrolling capture, see red box, move red box to where you want it, click for object capture, or shift+ctrl+click for scrolling capture, or menu for text capture.
NEW PROPOSED METHOD:
Trigger an object/scrolling capture, see red box, move red box to where you want it, click to select. Then get presented with a dialog with your 3 choices of copy object/region previously selected, or do a scrolling capture of the region previously selected, or do a text capture of the object selected.
ANOTHER POSSIBILITY:
Trigger an object/scrolling capture, then get presented with a dialog with your 3 choices of copy object/region, or do a scrolling capture , or do a text capture, then get shown red box to position.