Problem with conditional Installer page
 

I use a Modern UI installer structure with an entry for a custom page that launches one of my applications at the end of the installation process,
like
...
!insertmacro MUI_PAGE_STARTMENU Application $ICONS_GROUP
!insertmacro MUI_PAGE_INSTFILES
!define MUI_FINISHPAGE_RUN "$INSTDIR\MySpecialApp.exe"
!insertmacro MUI_PAGE_FINISH
!insertmacro MUI_UNPAGE_CONFIRM
!insertmacro MUI_UNPAGE_INSTFILES

Now I define 3 InstTypes, and Type 2 is without installing MySpecialApp.
When within the installation process I choose Type 2, I have to make sure that the "Run MySpecialApp now" page is not displayed for this InstType.
I fail repeatedly.
Mostly because "if[InstType2] - then[don't display that thing]" conditions must appear in sections or functions, but the installer page listn is not within a function, but apparently plain body text after the header.
Is it possible to switch an installer page on or off depending on the InstType value?
I didn't see any related thread in the forum. If there is any, and I was just too blind - a link will be my friend.

Thanks in advance,

John.

You've missed the FAQ which contains an entry about skipping pages.

To figure out which installation type was selected, you can use GetCurInstType, but it'd be simpler to check if $INSTDIR\MySpecialApp.exe exists.

So I tried ...

but sorry, I couldn't see any useful hint in the FAQ for this problem.
The main thing seems to be that I cannot build a function that is able to switch between the finish pages
MUI_FINISHPAGE_RUN "$INSTDIR\MySpecialApp.exe"
and
MUI_PAGE_FINISH
depending on the value of e.g. GetCurInstType. Either it isn't allowed to call macros containing that AutoCloseWindow parameter from within a function (as MUI_PAGE_FINISH is one of them), or it is impossible to use an if-then-condition outside a function. And I try to make an installer whose pages can be activated or deactivated depending on the InstallType, like
"if InstallType is [a], then call finishpage 1, else call finishpage 2"
I still can't figure out where this "else" has to be placed.
I hope anyone has a straw for me to clutch on.