Pause In AutoIt

#include <ButtonConstants.au3>
#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <MsgBoxConstants.au3>

HotKeySet("{f1}", "begin")
HotKeySet("{f3}", "pause")

#Region ### START Koda GUI section ### Form=
$Form1 = GUICreate("Form1", 336, 72, 192, 124)
$btn_begin = GUICtrlCreateButton("Start Click", 16, 16, 137, 33)
$btn_pause = GUICtrlCreateButton("Pause / Resume", 184, 16, 137, 33)
GUISetState(@SW_SHOW)
#EndRegion ### END Koda GUI section ###

While 1
    $nMsg = GUIGetMsg()
    Switch $nMsg
        Case $GUI_EVENT_CLOSE
            Exit
        Case $btn_begin
            begin()
        Case $btn_pause ; if i press f3 func begin() is pause, but when i click button pause not work, why?
            pause()
    EndSwitch
WEnd

Func begin()
    While 1
        ToolTip('Script is Running"', 500, 500)
        Delay(1000)
    WEnd
EndFunc ;==>begin

Func pause()
    ToolTip('Script is Paused"', 500, 500)
    MsgBox(0, "Paused", "Press OK to continue..")
EndFunc ;==>pause

Func Delay($sleep)
    For $i = 0 to $sleep
        Sleep(10)
        If GUIGetMsg() = $btn_pause Then
            pause()
            ExitLoop
        EndIf
    next
EndFunc