I can repro the issue. I suppose it was a bug and I will fix it in the nearest time. As workaround, I propose to move the mouse outside of the code block and set over another variable to show tooltip. After it, you can move the mouse back to previous code block (that is inside of smart outline region). The tooltip displayed correctly.
Thank you.
Thank you,
Misha Zhutov
http://submain.com - .NET Developer Tools