I originally posted this as an answer to a question in another category but my suggestion really belongs here. The question was "Can the mask appear on the image instead of the little side window?"
Until we have this functionality, here is a trick I've used when I really need to see what I am masking on top of the image. YMMV, but play around with it.
-Open the image in TS
-Add Color Overlay adjustment in a contrasting color with opacity at about 75% so you can still see the original image
--Open Color Overlay mask and create the mask you will use on the image. This simulates painting on the mask and is particularly helpful at a zoomed in level. When done, copy the mask and paste into whatever adjustment you need it on (inverting as needed). Then the Overlay can be deleted or just turned off.