Trying to blame me...

I was trying out my new developed server side web control. Everything worked exactly as planned until i took a look at the designer.
Because i was interested by the functionality i wasn't too worried about it's displaying in design time, but surprisingly it was displaying an error like:

Error creating control - MyControl
'MyCssClass' could not be set on property 'CssClass'

The first thing that crossed my mind was "I made a mistake!". But where?
After googling on internet, i found some fellows that were talking about the same issue. Their problem stopped at EnsureChildControls(). My problem didn't.

Looking for more information about this, i found that it wasn't my mistake. I found a bug in visual studio. The bug was reported here to Microsoft.