Well yeah I have a problem, I'm using trackball and I don't have middleclick, I even don't want to have it. i can't figure out what is the shortcut to paste it that way? because if you want to copy something from xterm you need to use middleclick. Ctrl+V and Shift+INS is using another clipboard.
Push both left and right buttons at the same time. If you prefer keyboard shortcuts take a look to this.
In most X11 programs, ShiftInsert should work – it pastes from the same "PRIMARY" selection that xterm copies to.
If you need to paste to Firefox or Chromium, though, you will need a program that synchronizes both selections, such as Klipper (KDE), Parcellite/Clipit (GNOME), or loliclip (generic). [The term is "clipboard manager".]
Alternatively, configure Xterm to copy to the "CLIPBOARD" selection instead, by adding one of the following to your