Other Carousel Animation Bugs

[michael-hawker]

This bug has been fixed, but two other animation bugs have been found:

• Animation bug when SelectedIndex does not change continuously.
• ManipulationDelta events related animation bug.

I will submit pr after all fixes are completed.

Originally posted by @HHChaos in #2829 (comment)

[michael-hawker]

@HHChaos apparently GitHub lets you create an issue from a comment, that's super handy, I had no idea this feature existed. Here's the other issue we said we needed to pull out for later too.