Create interface for a combobox based ListView column/cell

Since my Issue went by without being noticed, I tried to come up with an interface for a ComboBoxCellViewFrontend on my own.

I'm not sure if this is correct and I would be lieing if I knew what I wrote down there, but comparing that with the two 'examples' I had (the CheckBox and TextBox) I think that it's correct.

Also I'm not sure what to write at the Copyright line...Xamarin Studios? My name?