XUL panel steals input events

Hi,

I'm currently working on adding a set of preview tooltips to our firefox 
devtools (previewing images, CSS gradients, colors, etc ...) and I'm 
making use of XUL panels for this (specifically arrow type panels) cause 
they are nice and consistent with the rest of the Firefox UI (for 
instance with the download list top right).

One problem I'm facing now is that even with the noautofocus attribute 
set to true, when my panel appears (after I called openPopup(anchor)), 
the panel seems to be stealing my click events.
In fact, I then need to click twice instead of just once on the 
underlying anchor element to focus it.

I could use a XUL tooltip instead I guess, but then I would loose the 
nice doorhanger arrow thingy that I would like to use.

Is this a known issue? Is there already a bug for this? Should I open one?
Or perhaps there's an attribute I haven't yet seen that would fix this?

Thanks for your help!
Patrick