Forge implemented this feature where you can make 2 keys on 1 keybinding if you use shift, ctrl, alt as key basement on the keybinding.
Sadly IC2 Keys (and classic did it until the comming patch too) doesn't support that feature at all.
Reason being they ask the gamesettings if the key is pressed or not.
To fix that change this line:
to this:
This could fix also a issue with the mouse i found in IC2Classic. When you had 2 buttons mapped to a mouse that the second key was able to trigger the first key and cause it to get stuck on a state.
But i wasnt able to validate that yet.
Why i bring this extra thing up? Maybe because classics & exps Keybinding validator is equal. Even with different coding styles.
Still this feature should be supported...