I"ve had the same problem and was unable to fix it in any version of winrottgl.
if anyone else wants to try another sourceport, try rottexpr. although it's based on the icculus port i think it's pretty good.
can't post any links just search for: github LTCHIPS / rottexpr and go to releases for the windows binaries.
Support for resolutions from 320x200 all the way to 3840x2160
Adaptive HUD positioning (no more status bar being off to the side)
HUD scaling (HUD scaling for bottomless HUD coming later)
Support for bordered and borderless windowed modes
just be sure to make a new directory with all the files mentioned in the readme.