minor user friendliness issue

[Mistmatz]

For most menus pressing the 'Esc' key on the keyboard is similar to clicking the 'Exit' or sometimes 'Done' button in the menu window.

In the menu where one selects the plane type a squadron should upgrade to, this is not working.
Hitting the 'Esc' key didn't do anything in my case. Eventually this is because there is a 'Done' _and_ an 'Exit' option in this menu whereas the other menus I can think of have only one of the two fields.