Firstly, this software is so beautiful that it's hard to run away from. I use it on a very old 2009 iMac with a 27 inch screen and High Sierra 10.13.6.
Today I updated RUMLogNG from 5194 to 520 and have noticed some crowding of the button labels, but only with the IC-7610 control window. Changing the window size or shape makes no difference. The issue does not seem to occur anywhere else in the software.
This is due to major changes in macOS26. I was able to successfully test it with macOS 15, but not with older versions.
Unfortunately you have just these two options:
