(OSX) Inconsistent tab key behavior

[mkaemmerer]

On Mac OSX, WKWebView doesn't focus links or buttons when pressing the tab key. It only gives focus to text inputs (unless "fullKeyboardAccessEnabled" is turned on in system prefs).

This isn't a bug with DeskGap, but it's a really unfortunate consequence of WebKit design decisions. Edge, Firefox, Chrome and Electron all give tab focus to links by default. Arguably most developers (and most users as well) will be surprised and frustrated by this, so it would be a nice experience for DeskGap to patch the tab key behavior.