If I open larger documents (large in terms of dimensions, not pages), then mupdf's window is larger than the screen on which it is displayed. Please don't do that and open the window at most at screen height.
commit b1e19b3dfce37ac9dc300eeb5ce13bc86560a777 Author: Tor Andersson <tor.andersson@artifex.com> Date: Fri Nov 9 16:12:11 2018 +0100 Fix 696310: Limit the initial window size to fit on the screen. Also zoom to fit the window.