It would be OK if the export sized the window and the background image correctly. In Win 8.1 64 bit, this doesn’t currently work. Another option would be to make it so that the author could choose whether or not to allow the window to be resized, by introducing an option at the panel level, and would probably be the most flexible compromise.
For simple panels it shouldn’t be too difficult to scale and move the elements to let the end user resize the window, or to do something like the impOscar plugin and provide different sized presets.
The Puppeteer
http://godlike.com.au