OpenGL texture destruction under SDL confusion

Okay, sorry guys, but I’m totally confused.

When do my OpenGL textures get destroyed when I’m runing under Windows (and
therefore require reloading)?
Currently I’m trying to do it whenever the application is minimized, and I’m
not even able to detect that properly with my crummy code (SDL appears fail
to return SDL_APPACTIVE with gain = 0 sometimes, until I click on the
minimized icon, then suddenly that event gets pushed into the event queue).

Help, assistance, ideas and conversations welcome,