Assuming I change the contents of a control using a XamlReader and add the UIElement to the container of a control, what events are supposed to fire? There are times where the SizeChanged will fire, LayoutUpdated changing.. though there are other times where neither of these occur despite having changing the contents of a control. In my case, I am generating a thumbnail view of what's currently in view on a page. The user can change the content of the page and thus the thumbnail should update accordingly. Though, wiring to the LayoutUpdated, Loaded, SizeChanged aren't always reliable for when the contents have changed. I would just call my InvalidateThumbnail which uses a writeablebitmap, but it's too quick after setting the content and as a result I will get a blank thumbnail. At the moment, my hack (cringes) was to wait a few milliseconds before the UI is done rendering the actual new content and I can reliably create the thumbnail. I'd rather just trigger on an event every time though. Possible? What events should I look at? I've seen CompositeTarget.Rendering but that's not what I want.