You are talking about function naming convention. As function is typically an action (verb) that does not apply here.  There I see your point, but for property that does not make sense and IMO is confusing. 

Properties like enabled, pressed, etc. are all booleans so you would imagine from newTabRequested that it is just a boolean, but I checked many QML APIs and I do not see -ed used other than really special occasions (highlightedText), thus newWindowDetails would be better after all it is just data that will be used in future, just like any other property.

At minimum add a comment before the property to describe its use