The Issue

I have a mod-pack with Minecraft 1.12.2 and I installed World Handler in it. But I can't open the GUI because the "V" hotkey that opens the GUI is conflicting with another mod (Techguns) that uses the same hotkey that hasn't the option to change that specific hotkey.
So an option that allows you to change the hotkey that opens the GUI might help.

Just check the vanilla keybind options menu, its there

I found it. Thanks!