Other Backends, no sdl2-dependencies possible?

# Context

On compile process.

# Problem description & Solution

I try many months to compile every dev or crate version fom orbtk, but all will fail why sdl2 don't compile.

# Examples and MockUps

Give it a chance for a pure rust implementation? The sdl2-crate seems like not usable with a gnu-toolchain under windows. Another backend like sdl2?
