Kleiner Auszug aus der Hilfe mit zusammengeflicktem Beispiel 
#include <ButtonConstants.au3>
#include <GUIConstantsEx.au3>
#cs Aus der Hilfe:
$BS_AUTO3STATE 0x0006 Creates a three-state check box in which the state cycles
through selected, unavailable, and cleared each time the user selects the check box.
GUICtrlSetState ( controlID, state 
$GUI_UNCHECKED Radio, Checkbox or ListViewItem will be unchecked.
$GUI_CHECKED Radio, Checkbox or ListViewItem will be checked.
$GUI_INDETERMINATE Checkbox having the tristate attribute will be greyed.
#ce
[/autoit][autoit][/autoit][autoit]GUICreate("My GUI Checkbox")
[/autoit][autoit][/autoit][autoit]$check1 = GUICtrlCreateCheckbox("CHECKBOX 1", 10, 30, 120, 20,$BS_AUTO3STATE)
[/autoit][autoit][/autoit][autoit]GUISetState()
[/autoit][autoit][/autoit][autoit]While 1
$msg = GUIGetMsg()
If $msg = $GUI_EVENT_CLOSE Then ExitLoop
If $msg = $check1 Then MsgBox(0,"Info Checkbox1",GUICtrlRead($check1))
WEnd
Hi,
was fehlt dir denn noch? Es gibt doch Haken, Viereck, leer als Status
Mega
Aha, verstanden! Gute Frage. 
