I have seen this with a method with lots of overloads , particularly on MessageBox.Show (.....
When you start to add in all the parameters , you see initially all the overload options in a "block", when you select the first , the block goes black , and then a second or so later recovers and shows the list again. Select the next parameter and the same happens
It doesn't stop the show but its certainly distracting when you are "dashing" through a message box.
I must add its only methods with many overloads , normally you don't see a blip.