Haha, well agreed to an extent. The maximum number of controls 'on' the window at any one time is actually around 200 (and usually only around 40) - the rest are held in memory waiting to be connected to the visual tree when scrolling takes place. I have tried virtualising these 'properly' so that they are re-used but the overhead for them binding to their data is actually more costly than having them just sit in memory (which I certainly found surprising)

Fully understood. Thanks so much for your time - it's really helped! Uses for dependency properties seem to be a lot more obvious now too... Cheers! :)

If you are using WPF you can use an Animation, which will take care of restoring the original value when the animation ends (provided you configure it correctly). Otherwise you could create a disposable helper class that can animate a property value, including storing the original value and restoring it at the end.

Would this help? public static System.Collections.Generic.IEnumerable<T> Enumerate<T> ( params System.Collections.Generic.IEnumerable<T>[] Lists ) { foreach ( System.Collections.Generic.IEnumerable<T> list in Lists ) { foreach ( T t in list ) { yield return ( t ) ; } } yield break ; }

Hi, Take a look at the MessageBox.Show() overloads. There is one overload you parameterize with a IWin32Window handle (your Popup window) this should help you out showing your messagebox modal. greetz