[Project_owners] XUL override

[Onno Ekker]

Hi,

My Forward add-on adds a popup menu to Thunderbird's Forward button. 
This works fine by itself, but not in combination with another extension 
that also adds a dropdown menu to the same button. When both add-ons are 
loaded, my menu doesn't show up.

When I look at the DOM, I see two child nodes under toolbarbutton 
button-forward.
First comes the other menupopup, with no id and then comes mine with id 
button-forwardpopup.

Is there an easy way to merge these two menu's from XUL, when the other 
one doesn't have an id?
And if it can't be done, how and where can I do this from javascript?

Is there an easy way to detect if there are other menuitems from 
javascript, so I can insert a separator or something? Or always add a 
separator and hide it when there are no other menuitems?

Onno