What are the structures appended to the end of the main clause below?  They feel like participles, but they have pseudo-subjects.  Is it correct to use the objective pronouns in these structures? 

I slipped my backpack off, and we sat down at one of the metal tables overlooking the pool, him sipping his Mountain Dew and me groping for a pen and paper.

I hope everyone had a great Thanksgiving!

Thanks,
John
To join or leave this LISTSERV list, please visit the list's web interface at: http://listserv.muohio.edu/archives/ateg.html and select "Join or leave the list"

Visit ATEG's web site at http://ateg.org/