BGCOLOR reset after click on back

Hi,

I use SetCtlColors for change of backgroundcolor of Welcome page:

!define MUI_PAGE_CUSTOMFUNCTION_SHOW wel_show
!insertmacro MUI_PAGE_WELCOME

Function wel_show
FindWindow $1 "#32770" "" $HWNDPARENT
SetCtlColors $1 '' 0x000000
FunctionEnd

after click on next> and then on <back bgcolor is unchanged.
how can I fix it?

Thanks!

Why not use $MUI_HWND like say in the docs of the MUI

Thanks King,
for the direction, where I can search.
I try it.

Go to here and later scroll down to Custom functions.