Issue discussed here (Reaper 5/x64, portable installation) :
To make long things short, the midi editor ruler font is subject, under conditions difficult to reproduce, to unwanted changes. Worse : from this, no matter the changes done on other fonts related settings in the 'Theme tweak' window, or changes of theme, the font displayed remains the same. And, as there is no other available setting that could solve the problem...
From which, two solutions :
- either implementing a 'midi editor timeline font' setting in the 'Theme tweak' window, beside the already existing one for the arrange view,
- or making so that the font used in the midi editor remains ALWAYS and EXACTLY the same as the arrange ruler one.