About a GUI for Genode. That's in the roadmap for the beginning of 2013. So I began to think about it.
My first idea was an old idea, very simple. Each visual application (text or graphics) had it's own framebuffer (could be different size for each). When pressing Ctrl-PageUp or Ctrl-PageDown, you go from one to the other in a round-robin way. Each application occupy full-screen.
Now I am thinking about it for about half an hour ant it is evolving a bit.
First, this is not obvious that you have to use Ctrl-PageUp or Ctrl-PageDown. I suggest to use a small band on the left. Upper-Left would have a Ctrl-PageUp arrow icon. Down-Left would have a Ctrl-PageDown arrow icon. Each click on one of these arrows, change to the next application (fullscreen except the left region, and the still to come right region).
Now how do you launch a new application? My first idea was that one of the application was the launcher. Basically, similar the start page of Windows 8: one icon by available applications. Well that's look a bit wrong... why not category icons to the left, and to the right of it, a 'scrollable' list of icons for each application in the category.
Now, it is not funny to go around all the applications to find the launcher. I suggest to put the launcher icon in the middle of the left band. So now the launcher is always easy to get. As soon you click the launcher icon, your application disappears and the launcher take all the 'application' space and the launcher arrow become a go back arrow, to return to your application.
Now, a notification area seems important. I suggest to use the right part of the screen for it. In it, you only see the number of urgent, normal, information messages. As soon the mouse cursor goes to the right of the screen, the notifyer take all the 'application' area (almost full-screen) and a go-back to your application icon appears to the right of the screen (similar to the launcher).
It is very important that there is an inactive margin space between the application area and the left-part and between the application area and the right-part. That way, if there is a scroller in the application to the right, you will not activate the notifyer by mistake.
Perhaps, rather than have only the launcher in left-middle, there could also be an opened-application selector icon, for people that do open a lot of windows.
Ok, that's basically my suggestion, I am open for comments about it.