How do I make a combobox accept user input?

Still need help with this if possible!

Tried the following, but it didn't work:

Function SetReadOnly(Gadget, ReadOnly)
	
	Local EM_SETREADONLY = $CF
	Local ES_READONLY = $800 ; 2048
	Local NOT_ES_READONLY = -2049
	Local GWL_STYLE        = -16
	    
	Local Hwnd_Gadget
	Local Hwnd_Edit
	
	Local hWnd% = QueryObject(Gadget, 1)
	hWnd = GetParent(hWnd)
	
	; Get the handle of the gadget.
	;Hwnd_Gadget = QueryObject(Gadget, 1)
	
    ; Get the edit field handle.
   	Hwnd = FindWindowEx(Hwnd, 0, "", "")
    	
	SetWindowLong(Hwnd, GWL_STYLE, GetWindowLong(Hwnd, GWL_STYLE) And NOT_ES_READONLY)

	;If Hwnd_Edit <> 0 
		
		; Set or remove the read-only flag. (ES_ReadOnly)
     ;   SendMessage(Hwnd_Edit, EM_SETREADONLY, ReadOnly, 0)

	;End If

End Function