I compiled the example application from the attached archive which displays a QLineEdit, started it and entered äöäö.

This is the example app:

#include <QLineEdit> 
#include <QSettings> 
#include <QApplication> 
 
int main(int argc, char ** argv) 
{ 
    // swapping the next two lines fixes the bug 
    QSettings qs; 
    QApplication app(argc, argv); 
 
    QLineEdit edit; 
    edit.show(); 
    return app.exec(); 
} 

The problem is that when a QSettings object is created before QApplication is created, it breaks input of non-latin characters like umlauts ÄÖÜ in many widgets (tried with QLineEdit, QTableView).

Unicode characters that are not inputted by the user are displayed normally.

Except for this bug, QSettings works as expected.

If QSettings requires QApplication to be already created, a corresponding runtime warning and/or a note in the documentation would be very helpful.

Expected to see:
Correctly displayed unicode characters

Got instead:
Garbage. See screenshot in the archive