Error assigning TAdvPageControl->OnContextPopup

Using CB 10.3.3 Pro with the UI Pack on the 32 bit Clang platform.

I have an existing OnContextPopup event in a TAdvPageControl. I am trying to assign this event to a dynamicly created TAdvPageControl. I am getting an error saying the assigned function is not what the TAdvPageControl expected.  In the error message below the difference seems to be one of the TPoint value is Const, "const System::Types::TPoint &" and the other is not, "System::Types::TPoint &". How can I make this assignment?

//Existing event
void __fastcall TMainForm::AdvPageControl1ContextPopup(TObject *Sender, TPoint &MousePos, bool &Handled)
  //code here

//Assign to dynamicly created TAdvPageControl
TAdvPageControl *MyAdvPageControl = dynamic_cast<TAdvPageControl *>(Sender);
  MyAdvPageControl->OnContextPopup = AdvPageControl1ContextPopup;

[bcc32c Error]assigning to 'Vcl::Controls::TContextPopupEvent' (aka 'void ((__closure *))(System::TObject *, const System::Types::TPoint &, bool &) __attribute__((fastcall))') from incompatible type 'void (__closure *)(System::TObject *, System::Types::TPoint &, bool &) __attribute__((fastcall))'