Layout lifecycle

Hello

I'm currently trying to create a control by inheriting from Frame.
I override:

void OnSizeAllocated(double width, double height)
SizeRequest OnSizeRequest(double widthConstraint, double heightConstraint)

but unfortunately those methods get called very often so I think I'm not using them right. I could also not find something like suspendLayout/resumeLayout which I know from other frameworks to reduce the number of layout calls.

Does anyone know how the whole layout lifecycle works? Is there any documentation on this available? The API Xamarin documentation (OnSizeAllocated, OnSizeRequest) does not help much...

Thanks a lot!
Jürg