Finally trying out the GUI in order to learn how to improve alignments for conversion, based on the guide in this subforum. I figured out how to navigate, adjust bounding boxes, and save, which is great - but I'm confused about the purpose of the third window.
What I mean is, when I run the manual tool from main GUI window, it pops up three new windows:
1) tall rectangle with keyboard shortcuts
2) large window with full size frame of video being worked on
3) wide rectangle with four adjacent boxes, and a thumbnail of the current frame in the left-most box (the other three are black)
I don't understand the purpose of that third window.