So I actually kept the style above exactly the same. It seems like the problem was that when my "MyClass" object is null, an empty tool tip is displayed.
But when "MyClass" is null, I really want the tool tip to stop showing.
I get around this with the following datatrigger:
<DataTrigger Binding="{Binding Path=MyClass}" Value="{x:Null}">
<Setter Property="ToolTip" Value="{x:Null}" />
</DataTrigger>
The other triggers I had in my original post are no longer needed. By setting ToolTip
to null in the snippet above, the tool tip will automatically not show.