@telephon This is fine on mac, but any chance you could verify that it doesn't break anything on Linux?

I can also confirm: works on The Macintosh and it definitely did not work before.

both linux and windows would perform this hack/fix to the modifier:

        { if (mods & QKeyModifiers.control > 0) {cmods = cmods | 262144} } // Ctrl

Document.current.mouseDownAction = { |doc, x, y, mod ...args| 
    [mod,
        'alt:', mod.isAlt,
        'ctrl:', mod.isCtrl,
        'shift:', mod.isShift,
        'cmd:', mod.isCmd,
    ].postln
};

The bug this fixes was that toCocoa was not being used on Document key events as it already is on normal Views.

So as long as normal views are working on linux/windows they must also work on this Document view. If they didn't work then it wouldn't have anything to do with this PR anyway.

should we merge ?