uic-generated retranslateUI() discards current item selection in comboboxes

the uic-generated retranslateUI() code just clears the combobox and re-inserts all items from scratch. in that process, the current item index is lost.

possible solutions:

1. save the current index before re-populating the combobox and restore it afterwards. probably, signal emission of the underlying model should be suppressed during the entire process to avoid spurious index change notifications.
2. don't clear the combobox, but reset the items' text property. that seems the overall cleaner approach (e.g., doesn't necessitate suppressing all signals), but generates a lot more code.
3. reject the issue. if the user cares, he can implement variant 1. manually.