You can configure the Native Client for UNIX to use your own images for the splash screen and the webtop "display" pane.
The images used must be in XPM format. For good results, the splash screen image should be no larger than 300x400 and the webtop image should be no larger than 640x480.
app-defaults
directory:
/usr/lib/X11/app-defaults
$HOME/.tarantella/app-defaults
Ttwebtop
in a text editor.
*splashScreen*Pixmapfile
.
*demgrSW*Pixmapfile
.