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 <QLabel>
#include <QRect>
#include <QList>
#include <QMouseEvent>
class PixLabel : public QLabel
{
Q_OBJECT
public:
PixLabel();
QList<QRect> rects;
public slots:
void AddRect();
private:
void paintEvent(QPaintEvent * event);
void mousePressEvent(QMouseEvent * e);
};