Explicitly request High Dpi scaling on Qt >= 5.6

src/gui/main.cpp

@@ -180,6 +180,10 @@ int main(int argc, char *argv[]){
     // Enable HiDPI support
     qApp->setAttribute(Qt::AA_UseHighDpiPixmaps);
 #endif
+#if QT_VERSION >= QT_VERSION_CHECK(5, 6, 0)
+    // Explicitly request high dpi scaling
+    qApp->setAttribute(Qt::AA_EnableHighDpiScaling);
+#endif
 
     // Parse arguments
     switch (parseCommandLine(parser, &errorMessage)) {