Eh. n/m. Even when I did 1 shl, didn't seem right, and anyway, it isn't much of a mask if there are 16 categories and we use 10, of which those are the most common.
#include <QApplication>
#include "mainform.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWindow *mainWin = new MyWindow;
mainWin->show();
return app.exec();
}