Hi Walter, only yesterday I encountered the same issue. I have a workaround, but it it takes some time - maybe some people here on the forum could help us out - please chip in anyone with suggestions..
My exact situation was as follows: I use Preview Designer (Markab Version 2.14.0), controller 2.0.1-0008 on a Synology NAS (patters standard package), and originally Android play store App, which is Version 2.0 Beta 2. My android version is 4.3 jelly bean.
I had designed my UI panel in the designer using a 'custom panel' size of 323x579. I found this resolution here on this forum : http://www.openremote.org/display/forums/New+Device+Templates+for+Galaxy+S3+en+S4 from Eduardo Gil. Somewhere else on this forum Eduardo also recomeded an android app called "Screen Resolution" you can use on your phone to verify this. It will yield very similar result -plus/minus a few pixels..
This all worked fine for me, display and resoultuion wise on my S4, with one tiny exception that bugged me - the light switch sliders in my design have a little circle in them as the active marker used on the bar to indicate the desired lighting position. If the slider is set to anywhere except the extreme left or right all is fine, the little circle is displayed perfectly. The issue I had was that if the slider was at 0% or 100%, the icon/graphic of the little circle got cropped. For example, if it was all the way to the left at 0%, the left hand side of the circle was hidden and you could only see the right half of it. (I know - I have little to be worrying about )
This prompted me to look for a fix. I discovered on the forum talk of an updated Android web-console on source forge. its called "OpenRemote 2.1 Alpha Snapshot 2013-07-18". I installed it an found it solved my insanely picky issue with the slider rendering, but like you, it squashed my entire design into about a square inch at the top left of my S4s screen!
The only way so far I've found to address this is to create a new custom panel size in the designer, scaled at 1080x1920, and re-draw everything. Its is less than ideal, as my panel design is reasonably complex/large, and all my icons have to be re scaled to suit, and obviously don't look as nice when scaled up to a size that looks proportionally correct at 1080P Res. I only redid one sample page to prove the point..
The issue is, in as far as i can find out so far, is something to do with how open remote handles the HD res S4 screen. Somehow the older play store version is happy to interpret the Device Independent Pixel size of 323x579 and upscale it to fit correctly on the full HD screen. The newer versions of open-remote don't seem to do this scaling/auto-filling and need to be configured at full HD sizes to work correctly.
Maybe I've missed something somewhere along the way, but that's as far as I've gotten..
Any advice from any other Android users?