Can render a BMP but things are still going wrong

If Screen::RenderBMP is called before Screen::ScreenShot, the resulting BMP is blank.

NOTE: Testing colours: If -c 1 0 0 1 is passed, rectangle is rendered RED.
However, if Screen::ScreenShot is called, the rectangle is BLUE.

Something stupid going on with colours?
Tried messing with alpha channel, but things seem to always render regardless of their alpha value.

Should give up and do something actually important.