[theol0403]

From what I know, Xephyr is a virtual X server that creates a virtual screen and than displays its content as a application.
The kindles, being linux, run on a X window manager. X decides what goes on top, the DPI (pixel density), and manages everything about the windows including dragging and resizing windows.

So you ask, why not just have all my linux graphic applications display to the kindle X server directly? You can't because the kindle X server needs a special syntax. For an application to show on the kindles you need to name the application something like L:D_N:application_ID:Chess
Look up "xorg" here for an explanation of this syntax.

So if you have an application named "Chess" it won't show without all this other labeling.

Now you have two options: Either change the source code and recompile everything with this title or use a realtime name changer such as fronter (look this up here too).

Or you can run something like Xephyr (there are others).

Xephyr is a program which you can name it what you want in the commandline. It outputs in a kindle X window at the top level, the kindle treats it as a application. Then it opens a second X desktop server on port 1 (kindle X server is port 0). Then you specify what screen you want debian to output to, and all your normally named debian programs you can apt-get run on the kindle screen through this server.

Hope this helps