Silverlight combo popup not displayed correctly when window resizes

If I create a ComboBox from scratch, when the window is resized, the content is correctly displayed above/below, etc.

Why开发者_Go百科 this doesn't happen when you create your own Combo-derived class? What am I missing?

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Controls aren't magical. They need to be told that things happen (call a method on them) or look for them to happen (register for an event).

Find your Application.RootVisual and register for a SizeChanged event. Then resize your control. If it is in browser you may need to create a javascript bridge (hopefully not) that tells your SL object when the browser resizes.