On the Inkscape bug tracker, a bug was reported regarding some shortcuts involving Ctrl + Alt on Win32. This MR is a fix attempt for that bug.
From the commit message:
On Win32, "Ctrl + Alt" (= AltGr) can change the keyval for a key. Because _gtk_key_hash_lookup compares keyvals rather than keycodes, this meant that some accelerators involving the Ctrl + Alt modifiers were not detected. For example, on the Polish Programmers Layout, Ctrl + Alt + C produces ć. This made it impossible to trigger the accelerator Ctrl + Alt + C on that layout [0]. Since both Ctrl + Alt + C and ć are potentially valid accelerators, we have to check for and accept both variants. We do this by performing the key translation twice if Ctrl+Alt is present: Once with Ctrl+Alt modifiers, and once without. Then we accept either keyval.
I also removed the code from gdkkeys-win32.c that set MOD2 in the presence of AltGr because that doesn’t actually make a lot of sense with the way we do things now.