When I open Script Debugger I notice that the Call STack pane at the bottom of the window constantly resizes to some arbitrary size. When it's really bad, the lower pane occupies half of the total debugger size; most of the time, though, it only expands to about 6 rows high or so. I always drag the pane size down to the smallest it will go - about 3 lines. But next time I open it, it resizes again.
OS X 10.13.3