Implementing IViewport and setting content width & height

Hi All,

I have custom container that has Scroller as a child. TheScroller has an
another custom component as a viewport which implements IViewport (its not a
Group).

I'm trying to figure out at what point in the life cycle I need to calculate
contentHeight contentWidth in order to prevent unnecessary invalidations.

Currently I'm calculating it in the viewport's setActualSize method. The
viewport's contentHeight is set to a custom value but the contentWidth is
equal to explicit or measured width, it doesn't really need to be
calculated. This is the reason I am doing it in setActualSize.

I think doing it in setActualSize causes multiple invalidation cycles
because setting the contentWidth/Height will trigger the scroller to
invalidate the display list.

If anyone knows more on this or have suggestions please let me know.

Thanks,
Purush