Question: disable RichEditBox resize animation?

[FrayxRulez]

I have a multiline RichEditBox with automatic height and when lines are added or removed the box size changes are animated.
While this is a great behavior in various situations, it happens to be a problem in mine: I have to run various animations when the text is set to empty and the box resize makes them look pretty bad, as I can't really synchronize them.

As a temporary workaround, I'm setting the RichEditBox Height to a fixed value before running the animation, then I wait for the next SizeChanged event to set it back to double.NaN. While this seems to work I would like to know if there's a proper way to do this, as this one feels a bit flaky to me.