QMenu rollover highlight does not have disabled state on Windows 7

QMenu provides a rollover highlight when mousing over menu items on Windows 7.

This uses the correct colour (light blue) for the enabled state, but uses the same colour (rather than light gray) for the disabled state.

This makes it difficult to pick out disabled menu items, as although Windows 7 uses a lighter colour for the text it is quite similar to the text colour used for the enabled state.