Use GotFocus and lostfocus or other appropriate event/methods in the combobox to rewrite ON KEY LABEL "ESC"

>Hello *.*
>
>Which event(s) occurs after closing the list of a combobox ?
>
>I programmed my ESC key to release the form, but when I open a combobox and press ESC it must close first the list of combobox and pressing ESC again it will release my form.
>
>How can I do It?
>
>Thanks in advance.