This is my script now:
Only if I uncomment the line with MUI_PAGE_LICENSE it will show the header, but even then, not on the WELCOME and FINISH page.
!include "MUI.nsh"
Name "Test"
OutFile "Test.exe"
InstallDir "$PROGRAMFILES\Test"
!define MUI_HEADERIMAGE
!define MUI_HEADERIMAGE_BITMAP "${NSISDIR}\Contrib\Graphics\Header\nsis.bmp"
;!insertmacro MUI_PAGE_LICENSE "${NSISDIR}\Docs\Modern UI\License.txt"
!insertmacro MUI_PAGE_WELCOME
!insertmacro MUI_PAGE_INSTFILES
!insertmacro MUI_PAGE_FINISH
!insertmacro MUI_UNPAGE_WELCOME
!insertmacro MUI_UNPAGE_CONFIRM
!insertmacro MUI_UNPAGE_INSTFILES
!insertmacro MUI_UNPAGE_FINISH
!insertmacro MUI_LANGUAGE "Dutch"
Section "Test"
SetOutPath "$INSTDIR"
File "test.nsi"
WriteUninstaller "uninstall.exe"
SectionEnd
Section "Uninstall"
Delete $INSTDIR\test.nsi
Delete $INSTDIR\uninstall.exe
SectionEnd
Cheers!
Maurice