Prevent artifacts while reducing the size of popover content

I have a navigation controller inside a popover in an iPad app. The navigation controller contains a hierarchy of list views. All of them can have a different number of lines.

When I move from one to the other and vice versa, I resize the content using setContentSizeForViewInPopover:the correct height of the table. It works and looks good when a popover needs to grow to fit the view.

BUT, but if the new size is smaller than the current size of the popover, the system seems to start animating the size by “crossing out” (clipping) the part of the view that needs to be truncated, which is an ugly visual artifact. Ideally, I would like an additional part of the view remained visible and simply gradually overlapped by animation.

Does anyone know about this or better, how should I think about it?

Thank.