why i couldnot use onGUIInit in my installer script?

Question

I am trying to use onGUIInit function on my installer script but while compiling the script i am getting error that onguiinit already exits but there is only one onguiinit

ERROR:

Function: ".onGUIInit"
Error: Function named ".onGUIInit" already exists. 

Answer 1

!define MUI_CUSTOMFUNCTION_GUIINIT myonguiinit
!include MUI.nsh

Function myonguiinit
FunctionEnd