The warning box you speak of..is part of Windows..not AM..And even if the button was blank..They could still press it..and it would react the same way..
Also, they should still be able to press Esc..or CTRL + Q
I wonder what other engines do to avert this issue.
Other engines..most likely support Large Fonts.
It might be best to put a message where the user downloads the game..Simply telling them to make sure they are using
Normal sized fonts/icons before playing..
Similar to when we to leave a message that says..
Window users supported only