Oh wow, that's the first time anyone has actually pointed that out, sorry! The keyboard control for jumping is space, I'm surprised that I overlooked that even if it was done at the last minute.
Borderless window is disabled in my startup options on gamemaker and the game is set to go fullscreen when it starts, I even made it force a display reset and force fullscreen again with initialisation code to fix a refresh rate bug, so I'm not sure why it's doing that. I'll have to look into it, maybe starting it in a x2 or larger window would have been a better choice.