i adicionei um botão personalizado usando o Resource Hacker na página de diretório MUI do instalador, agora quero que, quando o botão for clicado, a caixa de texto padrão em que o usuário entra no InstallDir (o caminho em que o aplicativo está instalado) seja preenchida. algum texto especificado. por favor me ajude com o código?

Estou usando o plug-in ButtonEvent, mas não sei qual código escrever no manipulador de eventos. Atualmente, estou apenas exibindo uma caixa de mensagem quando o botão é clicado para garantir que o evento esteja funcionando. Por favor ajude

!define IDC_BUTTON_SETPATH 1200 (1200 is the ID OF THE BUTTON ADDED from Resource hacker)

;Pages

  !insertmacro MUI_PAGE_WELCOME

  !define MUI_PAGE_CUSTOMFUNCTION_SHOW DirectoryShow
  !define MUI_PAGE_CUSTOMFUNCTION_LEAVE DirectoryLeave

   !insertmacro MUI_PAGE_DIRECTORY

 !insertmacro MUI_PAGE_COMPONENTS
 !insertmacro MUI_PAGE_INSTFILES
 !insertmacro MUI_PAGE_FINISH

;--------------------------------

Function buttonclicked
   MessageBox MB_OK|MB_ICONEXCLAMATION "You Clicked Me "

  Abort

FunctionEnd

# Occurs on installer UI initialization.
Function myGuiInit

  # Create event handler for our parent window button.
  GetFunctionAddress $R3 buttonclicked
  ButtonEvent::AddEventHandler ${IDC_BUTTON_SETPATH} $R3

FunctionEnd

------------------------ NOVA PARTE EDITADA-- CÓDIGO PARA TRÊS BOTÕES PERSONALIZADOS --------------- ----

!include MUI2.nsh
; --------------------------------------------------

  !define IDC_BUTTON_CDRIVEPATH         1200
  !define IDC_BUTTON_DDRIVEPATH         1201
  !define IDC_BUTTON_EDRIVEPATH         1202

; --------------------------------------------------

# The event handler for our parent button is added in MyGUIInit.
!define MUI_CUSTOMFUNCTION_GUIINIT myGuiInit
  !define MUI_HEADERIMAGE
  !define MUI_HEADERIMAGE_BITMAP "${NSISDIR}\Contrib\Graphics\Header\pksicon.bmp" ; optional
  !define MUI_WELCOMEFINISHPAGE_BITMAP "${NSISDIR}\Contrib\Graphics\Wizard\pksleftimage.bmp" ;
;--------------------------------


XPStyle on


;Interface Settings

  !define MUI_ABORTWARNING

;--------------------------------
;Pages

  !insertmacro MUI_PAGE_WELCOME
  !insertmacro MUI_PAGE_LICENSE "${NSISDIR}\Docs\Modern UI\licensefile.txt"
!define MUI_PAGE_CUSTOMFUNCTION_SHOW DirectoryShow

   !insertmacro MUI_PAGE_DIRECTORY
 !insertmacro MUI_PAGE_COMPONENTS
 !insertmacro MUI_PAGE_INSTFILES
 !insertmacro MUI_PAGE_FINISH

 ; --------------------------------------------------

; Languages.

!insertmacro MUI_LANGUAGE English

; --------------------------------------------------


!macro SetDirPageInstallDir text
!if "${MUI_SYSVERSION}" < "2.0"
Push $0
FindWindow $0 "#32770" "" $HWNDPARENT
GetDlgItem $0 $0 0x3FB
SendMessage $0 ${WM_SETTEXT} 0 "STR:${text}"
Pop $0
!else
SendMessage $mui.DirectoryPage.Directory ${WM_SETTEXT} 0 "STR:${text}"
!endif
!macroend


# Called when the CDRIVEPATH button is pressed.
Function CDRIVEPATH

  MessageBox MB_OK|MB_ICONEXCLAMATION "The Software will be installed in : C:\ "

;In buttonclicked handler
!insertmacro SetDirPageInstallDir "C:\"

FunctionEnd
;--------------------------------

Function DDRIVEPATH

  MessageBox MB_OK|MB_ICONEXCLAMATION "The Software will be installed in : D:\ "

;In buttonclicked handler
!insertmacro SetDirPageInstallDir "D:\"

FunctionEnd
;--------------------------------
Function EDRIVEPATH

  MessageBox MB_OK|MB_ICONEXCLAMATION "The Software will be installed in : E:\ "

;In buttonclicked handler
!insertmacro SetDirPageInstallDir "E:\"

FunctionEnd
;--------------------------------

InstallDir $INSTDIR


# Occurs on installer UI initialization.
Function myGuiInit

  # Create event handler for our parent window button.
  GetFunctionAddress $R0 CDRIVEPATH
  ButtonEvent::AddEventHandler ${IDC_BUTTON_CDRIVEPATH} $R0

;  GetFunctionAddress $R1 EDRIVEPATH  **-----this line causes error**
;   ButtonEvent::AddEventHandler ${IDC_BUTTON_DDRIVEPATH} $R1   -----this line causes error

;  GetFunctionAddress $R2 EDRIVEPATH  **-----this line causes error**
;  ButtonEvent::AddEventHandler ${IDC_BUTTON_EDRIVEPATH} $R2  -----this line causes error



FunctionEnd

;------------------------------------------------

# Occurs on Directory page show.
Function DirectoryShow

  # Create event handler for our Directory page button. /NOTIFY makes
  # the button move to the next page when clicked.
  ButtonEvent::AddEventHandler ${IDC_BUTTON_CDRIVEPATH} 

  ButtonEvent::AddEventHandler ${IDC_BUTTON_DDRIVEPATH} 

  ButtonEvent::AddEventHandler ${IDC_BUTTON_EDRIVEPATH} 


  # Disable next button.
  GetDlgItem $R0 $HWNDPARENT 1
  EnableWindow $R0 0


FunctionEnd 


 ; --------------------------------------------------

;General

  ;Name and file
 Name NEW_FILL_TEXTBOX_BUTTONCLICK
OutFile NEW_FILL_TEXTBOX_BUTTONCLICK.exe


 Section

    DetailPrint "SUCCESSFULLY INSTALLED"

SectionEnd