Merge pull request #21379 from alfrix/set_style

Gui: Set QStyle to Fusion if not set

src/Gui/StartupProcess.cpp

@@ -295,7 +295,15 @@ void StartupPostProcess::setQtStyle()
 {
     ParameterGrp::handle hGrp = WindowParameter::getDefaultParameter()->GetGroup("MainWindow");
     auto qtStyle = hGrp->GetASCII("QtStyle");
+    if (qtStyle.empty()) {
+        qtStyle = "Fusion";
+        hGrp->SetASCII("QtStyle", qtStyle);
+    } else if (qtStyle == "System") {
+        // Special value to not set a QtStyle explicitly
+        return;
+    }
     QApplication::setStyle(QString::fromStdString(qtStyle));
+
 }
 
 void StartupPostProcess::checkOpenGL()