There seems to be an issue in QCombobox class when we make it editable by setting Editable property as true. Because, the pop-up menu vanishes immediately after its shown to the user. It does not allow the user to make a choice!
This scenario is observed in Nokia 5800 phone. Whereas the same code works well on Desktop.
If we do not set the editable mode to true, which is the default case, then it works fine.
I was wondering if it is a bug in Qt-Symbian? You can consider any Qt example, like basicdrawing example, and try it out. I am using Qt4.7.0-beta version.