TransformOperationTransition bug

Describe the bug this bug occurs with TransformOperationTransition and :pointerover psudoclass, when the pointer left the control, the transition still executing. Occurs with 0.10.1 and 0.10.2, but not with previous versions.

To Reproduce Use the follow styles:

<Style Selector="Control"> //any control can be affect
   <Setter Property="Transitions">
      	<Transitions>
		<TransformOperationsTransition Property="RenderTransform" Easing="ExponentialEaseOut" 
                                                                     Duration="0:0:0.2"/>
	</Transitions>
   </Setter>
</Style>
<Style Selector="Control:pointerover">
   <Setter Property="RenderTransform" Value="scale(0.95)"/>
</Style>

Expected behavior

Current Behavior

Desktop (please complete the following information):

• OS: Windows 10 20H2
• Version: Avalonia 0.10.2

[MarchingCube]

I will open this again since there is a bug that requires you to set this initial transform to begin with. It seems that due to broken binding completion priorities we end up in an infinite transition cycle.

So far this line seems to be a culprit: https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Base/PropertyStore/BindingEntry.cs#L75

Since it sets priority to Unset which gets picked up by animation as a value with very high priority and it tries to transition to it again.

On a side note - I was not able to reproduce scale(1) causing rendering to disappear.

[MarchingCube]

Transform transitions are a bit tricky currently, you might want to try using none instead of scale(1). Although both should work. I will take a look sometime during this week.