There is a 'CB_SETMINVISIBLE' constant but I do not know its value. It's used with the SendMessage API call.
See more info here on Micro$ofts
MSDN LibraryI think this works with XP only as well.
Al I have managed to get working is the items font height size:
; Combobox
; userlibs
; *******************************************************
; .lib "user32.dll"
; SendMessage%(hwnd, msg, wParam, mParam):"SendMessageA"
; *******************************************************
Const CB_SETITEMHEIGHT=$153
Const CB_SETMINVISIBLE=0 ; I don't know this value ???
win=CreateWindow("test",50,20,200,100,Desktop(),1+2)
cb=CreateComboBox(10,10,100,0,win)
For i=0 To 20
AddGadgetItem cb,"Item "+i
Next
SelectGadgetItem cb,0
SendMessage QueryObject(cb,1),CB_SETITEMHEIGHT,0,30
;; SendMessage QueryObject(cb,1),CB_SETMINVISIBLE,0,10
Repeat
Until WaitEvent()=$803
End