DataTemplate::LoadContent returns an object with an extra ref count

[jevansaks]

See #1954 for more information, but the problem is that DataTemplate::LoadContent returns an extra reference on the peer object that it retuns. LoadContent and XamlReader::Load do similar things but XamlReader::Load (in the LoadImpl method) calls UnpegNoRef() which takes care of this extra reference. LoadContent doesn't have this and as a result the object returned to callers has a ref count of 2 on it and there's no obvious way to fix this extra reference.

In ItemsRepeater I'm proposing we work around this by adding the object to a Panel's Children collection and immediately removing it, but we should fix this so we don't need that work around with WinUI 3.0.

[lukeblevins]

@jevansaks Do you think ListView, TabViewListView, or GridView would be affected by this bug with DataTemplate? I have no way to inspect the implementation of those controls, but it seems reasonable enough to suspect they would considering the context around this TabView issue I reported #3597.

If so, is there a workaround to allow the proper release of TabViewItem content?

I don't mention this to nag or derail the purpose of this issue. Instead, I see a possible correlation considering the controls I mentioned also leverage DataTemplate.

[StephenLPeters]

This issue has been fixed in the OS code and will be included in a future release.