Fix wait query regression

shamefully introduced by myself in d61b659345385386ba8d3fff1158fe0923ae7ab8. 
(but there was no test case covering the missed thing :p)

and while at it : simplified and clarified handling of multiple components in a single request. (mostly DRY).

Renamed the class.

And it was also needed because I used a super(klass, self) with the bad klass value..