“事件”选项卡随机出现并在VS 2008中消失

I know it's a minor annoyance.. but it's still an annoyance and it baffles me.. About 3 months ago I was using VS 2008 and when I went to the "Properties" tab there was the little lightning bolt for events(in design mode). Then it suddenly went away.. about a week later I discovered that if I didn't have the properties tab "stickied", then the events thing would be there, but not when its stickied. I know it's a minor annoyance.. but it's still