You can reach the widgets on the .ui with the ui variable in your cpp code. Eg. Code: ui->myComboBox->doStuff(); About what do do with a combo box, here is some doc: http://doc.qt.nokia.com/4.6/qcombobox.html Qt is _very well_ documented, you should be able to find anything you want to know about it!
ui->myComboBox->doStuff();