Explore glop integration

[kaveh808]

Let's see if we can implement the glfw functionality using glop, which some of you prefer.

The idea would be a rewrite of minimal-ui.lisp using glop.

[JMC-design]

So while writing a key binding back end for glop I noticed it doesn't accept modifiers in it's on-key on-button methods, nor does it report modifiers in it's events. That's probably acceptable in games, but not for an application I think, especially if you want to allow people to customize their keybindings.

[kaveh808]

Yeah, we definitely need modifiers.