Determining Value Change in Combobox

I need to determine when a key has been pressed (value changed) in a combobox control of the command bar Where the .DropDownListStyle = True .

Thanks, but I need something which will tell me what the changes were like a "CommandBarKeyUp" event - as the KeyDown event fires before the changes can be read from the combo/edit box.

Try creating a variable that is global to the form.  Use it to store the current value of the combobox.  In the CommandBars_Update() event, check the current value of the combobox against the value stored in the global variable.  If it is different, then the value has changed.