That's all well and good, but ... the combobox.Text VALUE is NOT what's DISPLAYED as the TEXT parameter!
combobox.Items.Add( 'abc=def' );
combobox.Items.Add( 'uvw=xyz' );
...
// user select first item and the combobox SHOWS: "def"
However ...
ShowMessage( IfThen( (combobox.Items[0] = combobox.Text), 'true', 'false' ) ); // shows "true"
ShowMessage( IfThen( (combobox.Text = 'def'), 'true', 'false' ) ); // shows "false"
because
ShowMessage( combobox.Text ); // shows 'abc=def'
BTW, this makes eliminating dups rather complicated.