ListView highlight occasionally gets stuck

This was seen with QML from qt:4.7 at 5498dcd7b10e147734a3414cab824b8b435aa3d9

Not sure how to reproduce it reliably, but it happens sometimes when
clicking an item in the left-hand side ListView in Qt Component's
stretchbench test app, perhaps when the mouse pointer is not completely
still when the click occurs. See attached snapshot.