Karmic's gdm does not support custom commands, e.g. launching the kiosk browser

[rbasch]

The version of gdm in Karmic (2.28) does not seem to support defining custom commands. We currently use that feature (in 2.20) to define a command to launch the kiosk mode browser, so we will apparently have to rethink that, as well as our custom theme (#430).

[rbasch]

We can use the autostart facility in the new gdm to add an application to the login window. For example, we could write a simple gtk application with a button that brings up a confirmation dialog, and have it launched in the login window by creating an appropriate .desktop file in /usr/share/gdm/autostart/LoginWindow/. (Screen shots of a proof-of-principle are in /mit/rbasch/Public/karmic-kiosk-button.png and karmic-kiosk-dialog.png).

For a bit more work, we could also write an applet with an icon in the login window tray area, that, say, pops up a menu of pre-login options when clicked.