Fix Windows min/max animation on frameless windows

- Frameless windows disappeared or appears when minimized and maximized
on Windows. This commit fixes that.
Make sure frame is frameless
Merge branch 'master' into windows-min-max-animation
Fix code style to be <= 80 lines
Merge pull request #800 from frankhale/windows-min-max-animation

Fix Windows min/max animation on frameless windows