I was able to change the system DPI by using app settings and changing DPI for System and System UI. But I am running into the same problem with the keyboard. Even when it is set to 320, the floating keyboard and any pop up windows from the regular keyboard are fubar. I don't want to use the floating keyboard, but I can't find a way to disable it and it seems to come back periodically. Either need to fix the resolution issue or figure out how to disable some of the keyboard modes.
Treo 650 -> Blackjack -> Tytn I -> Tytn 2 -> Palm Pre -> Hero -> Evo -> Evo 3D -> Galaxy Nexus -> Galaxy S III -> Nexus 4