To operate on a combobox object and based on your requirement, you can use any of these functions
capturetofile - Get the entires of list box and dump it to a file
click - Click on a combo box
comboselect - Select an item from the combo box list or menu item
hidelist - Hide the combo box drop down list
selectindex - Select combo box item based on index
settextvalue - Set a text in the combo box list
showlist - Show the combo box drop down list
verifydropdown - Verify whether the drop down list pops up
verifyhidelist - Verify whether the drop down list is in hidden state
verifyselect - Verify whether the item is selected in the combo box list
verifysettext - Verify whether the text set is available
verifyshowlist - Verify whether the drop down list is displayed
Linux Desktop Testing Project