For anyone experiencing the same issue....
(and suffering that problem only in the conversation viewer)

Here the solution!

rtcom-messaging-ui uses the browser to view sms/chat conversations with a set of css and js files...
So the problem is into the browser.

Digging and searching, comparing my actual files with a previous backup, i found that into the folder:
/usr/lib/microb-engine/components/
there is a symbolic link:

libwidgetutils.so -> /usr/lib/libwidgetutils.so.0.0.0

Where this lib is also required by rtcom-messaging-ui:
http://maemo.org/packages/package_in...1.4.1-6.1+0m5/

Check the symbolic link and fix it if not present, kill all the browser and messaging process and retry. (btw, a reboot is better)

Now the scrollbar should be vanished and the selection cursor (like the one in the browser) should be available.
The result should be: