I noticed some awkward behavior with the flipper where it seems to scale if the content shrinks (requires less space than before), in my case when a combobox selection is reset. Luckily I happened to have two identical flippers with identical content:

It seems like a scale transformation is applied on the Viewport2DVisual3D (this is the right flipper):

And here's left for comparison:

I guess the issue might com from the following piece in Plane3D:
private void Update3D()
{
// Use GetDescendantBounds for sizing and centering since DesiredSize includes layout whitespace, whereas GetDescendantBounds
// is tighter
var logicalBounds = VisualTreeHelper.GetDescendantBounds(_logicalChild);
var w = logicalBounds.Width;
var h = logicalBounds.Height;
...
_scaleTransform.ScaleX = w;
_scaleTransform.ScaleY = h;
I'm not sure why this doesn't match the actual content size when it shrinks, (or actually, maybe this isn't called when the content shrinks?) but flipping the card back and forth fixes the scale.
I'm sorry for the huge screenshots, they were taken at 200% scale.
I noticed some awkward behavior with the flipper where it seems to scale if the content shrinks (requires less space than before), in my case when a combobox selection is reset. Luckily I happened to have two identical flippers with identical content:

It seems like a scale transformation is applied on the Viewport2DVisual3D (this is the right flipper):

And here's left for comparison:

I guess the issue might com from the following piece in Plane3D:
I'm not sure why this doesn't match the actual content size when it shrinks, (or actually, maybe this isn't called when the content shrinks?) but flipping the card back and forth fixes the scale.
I'm sorry for the huge screenshots, they were taken at 200% scale.