Pytest fails

[ArneVoss]

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Describe the bug

Please give a short and clear description of what the bug is and what you expected to happen. Please provide instructions and data to reproduce the problem (model, jcl, etc.). Please provide the smallest working example that reproduces the problem.

The Gui test show the following error message
app = QApplication([])
RuntimeError: Please destroy the QApplication singleton before creating a new QApplication instance.

[ArneVoss]

Closed by #45