Application windows don't show with window icon

[ruimaciel]

Describe the bug
When QtPass is launched for the first time and QtPass shows its first-time use dialog boxes (i.e., "password store not initialized", "read acces users", and "Configuration"), these windows don't show with a Windows dialog. Consequently, desktop environments such as Ubuntu's GNOME show the default placeholder application window instead of QtPass' own application icon.

To Reproduce
Steps to reproduce the behavior on Linux (Ubuntu 23.04):

1. Delete ~/.password-store,
2. Launch QtPass,
3. See missing application icon from dialog boxes.

Expected behavior
The same app icon shown in QtPass' main window should be used on all dialog boxes.

Screenshots

Desktop (please complete the following information):

• OS/Distribution: Ubuntu 23.04 (should also impact other OSes)
• Version: current mainline (1.40.0 ?)