#include <GUIConstantsEx.au3>
$hGUI = GUICreate("Test Script", 300, 400)
$iFirst_CB = GUICtrlCreateDummy()+1
$iTop = 20
For $i = 1 To 10
GUICtrlCreateCheckbox("CheckBox" & $i, 20, $iTop)
$iTop += 20
Next
$iLast_CB = GUICtrlCreateDummy()-1
$iCheckAll_CB = GUICtrlCreateCheckbox("Check All", 20, 270)
GUISetState(@SW_SHOW, $hGUI)
While 1
Switch GUIGetMsg()
Case $GUI_EVENT_CLOSE
Exit
Case $iCheckAll_CB
$iState = GUICtrlRead($iCheckAll_CB)
For $iCB = $iFirst_CB To $iLast_CB
GUICtrlSetState($iCB, $iState)
Next
EndSwitch
WEnd