Please describe the problem:
Wow, I found an obscure one. :)  The tooltips that open when you mouse over a
calendar event do not understand the scroll wheel event.  What happens is the
tooltip gets "stuck" open and it's impossible to get rid of the tooltip.

To recreate, you need to have a mouse with a middle scroll wheel.  Put calendar
into monthly view and then do a mouse over an event.  The tooltip will open and
display.  If you then scroll with your middle mouse button it flips up or down
one month but the tooltip remains.  It is then "stuck" and impossible to remove.
 It's sitting over the top of the screen.  You have to close Evolution
completely to get rid of it.

I'm attaching a shot to show you how it's floating over the top of the window. 
I took an xterm window and put it over Evolution and the tooltip is still
hanging over the top.  

Steps to reproduce:
1. 
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Actual results:


Expected results:


Does this happen every time?


Other information: