style not drawing menu section/separator if 1st in menu

[René J. V. Bertin]

René J. V. Bertin wrote:

>> Always test with Fusion style. If it works there, the bug is in QtCurve.
> 
> FWIW the same thing happens with both Breeze and Oxygen in their Qt4 versions.

For future reference:

In the end I got out the debugger and traced the issue into Qt, realising that a 
style hint was introduced in Qt5 that allows styles to indicate that they render 
texted separators: SH_Menu_SupportsSections. Returning true for this hint fixes 
the issue.

R.