Usually in linux you can mark text and the point the mouse somewhere and press both buttons simultaneously and it will paste the marked text.
I recently installed the new version of Ubuntu (9.10) and I see this feature is not working.
How do I enable it?
Actually the default behaviour always was to press the third button, i.e. the scroll wheel to paste. Most probably the default setting doesn't include the "Emulate3Button" directive anymore, because everybody had a scroll-wheeled mouse for years nowadays :)
What can you do? Search for the "Emulate 3 buttons" option in your mouse control panel; alternatively edit /etc/X11/xorg.conf and add the line to the corresponding section like this :
<rant> Please notice that most current distros don't come with /etc/X11/xorg.conf anymore; the X server automatically sets up itself, with the very annoying consequence that when the default automatic setting doesn't fit your taste, it's a pure PITA to change.</rant>
If X.org is using