Each version of Qt supports a set of OpenGL levels; the level displayed
to the user is only as high as what was supported at compile-time. Hence
it should be harmless to degrade gracefully to previous Qt versions.
Versions of Qt < 4.7 do not have a QString constructor from QChar*
without specifying the size of the string. However, since the QString
is copy-on-write, the QString object can be passed to the copy
constructor of the return value directly!