Hello, Thanks for your answers. After looking at it a bit better. Here is what I added to make it work correctly.

$main->AddCombobox(     
        -name   => "combo_box1",
        -width  => 120,
        -height => 110,
        #-tabstop=> 1,
        -pos => [5,160],
        -dropdownlist=> 0,
        
        );

$main->combo_box1->InsertItem("One");
[download]

Thanks once again for your help.