Fun fact is, I'm telling you the following because this answer helped me out; however, this might help you: add the following line to your 'build.prop' file, to over-ride these settings, maybe? anyway, it's:
(clicking it will take you to the reddit page where I found it).
this worked for me, but my actual home pages and other 'desktop' screens were still much smaller...I'm hoping some guys at XDA Developers will post some new stuff on this; meanwhile, I'm also hoping some of the few apps that currently work with WindowsAndroid might include video stuff, like Youtube, Netflix, Hulu, the system video player, and that these apps, in full-screen mode, might fill the space better.
Hope this helped you a little--the way you posed your question certainly helped me.
Thanks, guys Mike Denney