You can use the font 'Marlett' to have the original characters.
$hGUI = GUICreate("Test", 200, 150)
$hCheck1 = GUICtrlCreateLabel("", 10, 10, 20, 20, 0x1201)
GUICtrlSetFont(-1, 19, 400, 0, "Marlett")
GUICtrlSetBkColor(-1, 0xFFFFFF)
$hLbl1 = GUICtrlCreateLabel("A user-drawn checkbox", 35, 15, 200, 20)
$hCheck2 = GUICtrlCreateLabel("", 10, 50, 25, 25, 0x1201)
GUICtrlSetFont(-1, 24, 400, 0, "Marlett")
GUICtrlSetBkColor(-1, 0xFFFFFF)
$hLbl2 = GUICtrlCreateLabel("Another user-drawn checkbox", 40, 57, 200, 20)
GUICtrlCreateCheckbox("An API-created checkbox", 10, 100, 200, 20)
GUISetState()
While 1
Switch GUIGetMsg()
Case -3
Exit
Case $hCheck1, $hLbl1
Switch GUICtrlRead($hCheck1)
Case ""
GUICtrlSetData($hCheck1, "a")
Case Else
GUICtrlSetData($hCheck1, "")
EndSwitch
Case $hCheck2, $hLbl2
Switch GUICtrlRead($hCheck2)
Case ""
GUICtrlSetData($hCheck2, "r")
Case Else
GUICtrlSetData($hCheck2, "")
EndSwitch
EndSwitch
WEnd