Hi all,

I am working on a project that uses the QFileDialog class, in native mode.
The project uses Qt 5.9.3 right now.

All is working fine on Windows, Mac, and Ubuntu.
But on Linux Mint (19.1 Cinnamon) when using that class, the dialog is shown, but without certain layout graphics, like the WRONG-part in following image:


The CORRECT-part is a screenshot made of the same dialog but shown via the built-in texteditor of Mint.

This behaviour is also the case if showing this QFileDialog is the only thing that is done within my program.
I tested it on 2 different Linux Mint computers.
The program is running via an AppImage. The generated AppImage contains all the necessary Qt libraries. The AppImage is generated using the linuxdeployqt-tool.

Does anyone have an idea what might be the cause of this incorrectly displayed dialog?