No, it's even dirtier like in https://github.com/geany/geany/blob/88a0bfcb3618b2533a5e7e253c7ef7af3c0b0590....
Ok, so its effectively relative to the installation dir, which means its ok if the OPs USB drive shows up as F: instead of G: when moved from machine to machine. Geany will still find its system files.
And I see below Macos emulates that :-)