Add SDL_GetWindowBordersSize()

[TimDiekmann]

Add SDL_GetWindowBordersSize() as pub fn border_size(&self) -> (i32, i32, i32, i32) to Window

[TimDiekmann]

The checks failed btw. because your travis is broken.

The command "pip install 'travis-cargo<0.2' --user &&
  export PATH=$HOME/.local/bin:$PATH &&
  export PATH=~/Library/Python/2.7/bin:$PATH
  " failed and exited with 127 during .

[Cobrand]

According to the documentation, this function can fail, so it should return a Result<(i32, i32, i32, i32)>. Also, this method is only supported with X11 (I assume it sends an error otherwise), so we should specify that in the function's documentation as well.

Why i32s? Can the borders be negative somehow? I think it would be better to have u16 or u32 instead here, if we can confirm that this never goes below 0.

Otherwise LGTM.

[TimDiekmann]

According to the documentation, this function can fail, so it should return a Result<(i32, i32, i32, i32)>

It will always return (0, 0, 0, 0) if it fails, so it's well defined behavior imo.

[Cobrand]

And how do you tell the difference between a failure and a borderless window?

[TimDiekmann]

Good point... Fixed, besides this function shouldn't be used for detecting a borderless window ;)

[Cobrand]

You forgot to change this part of the documentation.

[TimDiekmann]

I removed this part since it's implicit in the return type ;)