“Bold” style is not available for “Sans Serif” font on QT5

[JieLiu]

We just moved our application from QT4 to QT5. We found the "Bold" style is not avialble for "Sans Serif" font on QT5. I can tell from the QFontDialog which looks below:

I also use the following code to dump all available styles under "Sans Serif"

QFontDatabase db;
auto list = db.styles("Sans Serif");
for(auto& l : list)
    std::cout << l << " ";

I got the same list which is Normal, Italic and Oblique. However I can see the Bold and Bold Italic options on QT4. My question is how the mapping from font to font style is implemented. Am I able to configure something to make the "Bold" avalialble for "Sans Serif" font in QT5.