https://developer.apple.com/library/content/samplecode/RoundTransparentWindow/Listings/Classes_CustomWindow_m.html#//apple_ref/doc/uid/DTS10000401-Classes_CustomWindow_m-DontLinkElementID_8
https://git.gnome.org/browse/gtk+/tree/gdk/quartz/GdkQuartzNSWindow.c
http://www.cocoawithlove.com/2008/12/drawing-custom-window-on-mac-os-x.html
http://www.cocoabuilder.com/archive/cocoa/129590-moving-borderless-window.html
http://stackoverflow.com/questions/7245725/all-sides-resize-of-borderless-nswindow-in-lion
http://stackoverflow.com/questions/15782176/how-to-make-a-custom-window-resizable-from-all-sides
http://www.cocoabuilder.com/archive/cocoa/97795-resizable-borderless-window.html
http://www.cocoabuilder.com/archive/cocoa/229815-borderless-and-resize.html
https://web.archive.org/web/20160409030454/http://cocoadev.com/BorderlessWindow