I would like to check the appearance of my GUI while coding, for several OS where it should be distributed.
How can I do ?
The problem is that the ‘previsualisation’ proposed by QT Designer is very different from the appearance of the distributed release. I even have spots in tabs that appear with same font and size in ‘previsualisation’ but have different sizes on Windows... I work with: python 3.5, a GUI designed with QT Designer, developed on mac OS 10.11 and shared with Windows 7 and Windows 10 systems (installed with a recent pyinstaller)
The preview uses some approximation of the final style drawn completely by Qt, but the style used "for real" in most platform plug-ins either employs real, native widgets, or emulates them asking for theme parts straight from the machine where it's running. So, it's not possible to have a completely faithful preview unless you use a style that is always drawn completely by Qt (such as Fusion).
Long story short: to see how your application will really look on different platforms you'll have to test it "for real".
appearance of my GUI in several OS