Request: Improvements in window mode

[zysrc]

Thanks for this fast and lightweight app. I like to open small images in window mode, and large ones in fullscreen mode. And I often use Magnet to resize window size and position.

Request some improvements:

1. Add a shortcut to quickly switch between window and fullscreen mode for currently opened image. eg., Option+Command+F.
2. Make it possible to resize window via Magnet. Currently I can't use Magnet to do so.

Thanks