feature: add maximize-frame and minimize-frame command for lem sdl2 version.

[sakurawald]

The issue: #1583

[sakurawald]

To start up lem editor and maximize it, append this to init.lisp:

(lem-sdl2/frame:maximize-frame)

[cxxxr]

That's good.
If I had to say something, I'd like to put it in the same package as toggle-frame-fullscreen and unify the interface.
I also want to make it compatible with other than SDL2.

https://github.com/lem-project/lem/pull/831/files
Wouldn't it be nice to define the interface like the PR of the link destination?

[cxxxr]

I tried it on a macos, but it seems that the process will end abnormally if you don't use sdl2:in-main-thread.

I was able to get it working on macOS by doing the following

(sdl2:in-main-thread ()
    (sdl2:maximize-window (lem-sdl2/display::display-window (lem-sdl2/display:current-display))))

[sakurawald]

I tried it on a macos, but it seems that the process will end abnormally if you don't use sdl2:in-main-thread.

I was able to get it working on macOS by doing the following

(sdl2:in-main-thread ()
    (sdl2:maximize-window (lem-sdl2/display::display-window (lem-sdl2/display:current-display))))

Hah, sorry, i forget about this.
It works well in linux, i am not very sure about it in other platforms.

I have modified the source, and you can help me modify it if anything is wrong.

[cxxxr]

Thank you.
Can I merge it and then make changes?
I'll move the command definitions to lem-core/commands/frame.

[sakurawald]

Thank you. Can I merge it and then make changes? I'll move the command definitions to lem-core/commands/frame.

Sure!