fix #35576

I finally figured out why there is a difference between Windows, Linux on one side and Mac on the other side when it comes to tab focus. The option All controls should be selected as shown in the link below:
http://www.mactricksandtips.com/2008/10/use-tab-to-switch-between-dialog-buttons.html

I will remove all the other OS dependent code when it comes to focus policies in a different PR, but the code from this PR assumes that if the user wants to use the keyboard for tabbing he must select the All controls option.
@lasconic sure