For years Qt Creator and QDS UIs are broken for me when using displays with different scales/resolutions. Menus and sub-menus on wrong position, text that doesn't fit, buttons with incorrect size and so on...

While investigating the issue to try to create a reproducer, I came across this code: 

Qt::HighDpiScaleFactorRoundingPolicy StyleHelper::defaultHighDpiScaleFactorRoundingPolicy()
{
    return HostOsInfo::isMacHost() ? Qt::HighDpiScaleFactorRoundingPolicy::Unset
                                   : Qt::HighDpiScaleFactorRoundingPolicy::Round;
}
 

Setting  Qt::HighDpiScaleFactorRoundingPolicy::Round in a simple Qt application gives the same problem I was seeing in Qt Creator and Design Studio.

Unfortunately, this is the default setting in Qt Design Studio, and is not easing to find, but it is available in the configuration options.

My proposal is to have  Qt::HighDpiScaleFactorRoundingPolicy::Unset as default on Qt Design Studio. Or make it easier to quick find this settings and improve documentation around it.