I don't know how would locate that commit, not that I would be able to contribute much in any case. But perhaps is the solution to give it a max default height of e.g. 800 pix then the user can at least see there are options at the bottom? And can move the window around to access them? For me, now I know they are there I can do a work around by setting default values on a small image, or also I have figured that the settings are are stored in ~/.config/GIMP/2.10/printrc Steve
Also just compiled and installed 5.3.4 from source, problem still exists.
I have also run into this problem, from within Gimp the gutenprint gui controls are off the bottom of the screen (I didn't even realise they existed until seeing this report) Linux Mint XFCE 21.2 Gimp 2.10.30 Gutenprint 5.3.3 This makes the gutenprint gui unusable for high quality images
Edited to remove. I was talking rubbish.
I just updated to the latest version (6.0.055) and immediately found that this bug...