- Open about:debugging-new
- Click "Inspect" button of one of tabs
(Open devtools in new tab)
- Show context menu on the dom inspector of the tab
The context menu should be same to normal dom inspector.
The context is not for the inspector. For example, context menu of normal inspector has "Create new Node" item though, the inspector which opened from about:debugging page does not have.
Please see the attachment of the original bug 1515265.
The reason seems what the context menu event does not send to the parents correctly.
(I have taken various advices from Masayuki during investigating! Thank you very much!)
I had been investigating how the event walks to the parents with the attached patch. When show the context menu of normal inspector which can be opened by Tools -> Web Developer -> Inspector, traces like below from event source to the root.
The other hand, when show the context menu of inspector of new tab, traces like below.
When we compare, the latter we can know that the event sends to <browser> element from #document via two EventTarget that does not have node name, then parents which is between #document and <browser> was shortcutted. I invesigated though, the two EventTarget was nsGlobalWindowInner and InProcessTabChildMessageManger. And since this InProcessTabChildMessageManger points <browser> as next parent, the event was shortcutted.
I investigated why got such the behavior though, mParentTarget which sets in nsGlobalWindowInner::UpdateParentTarget was same instance of InProcessTabChildMessageManger which has <browser> as the parent for all of nsGlobalWindowInner instances.
So, after through the 1st nsGlobalWindowInner, the parent will be same, then go to <browser>.
I'm not familiar with this related technology though, regardless all of xul of about:* page is running on main process only, use the message manager. This might be cause makes weird behavior?