Alt key on windowed adobe air app, causes massive freezes

Hello, we noticed a very strange behaviour that completly kills our game performance : 

Pushing alt key on a windowed adobe air app (built with normal chrome and type) seems to switch and enable the windows system menu (like alt-space), causing massive freezes and lags. Pushing a second time alt key disable that invisible menu and stops freezing the app.

Seems to happen on a large variety of apps (not only our game). So far our code is not involved...

Happening from air 29 to last version released (maybe previous versions too, didn't test)

Not happening on mac or windows 7 so far...

Might be there since a very very long time, but no clue at the moment.

Disabling alt key with soft like AutoHotKey seems to do the trick, but not a very satisfying solution...

I've created a post on the bug tracker, but was wondering if someone already managed to avoid this.

https://tracker.adobe.com/#/view/AIR-4198912

Thanks.