That would be 6, not 4... wrong command syntax anyway (dunno why, not going to read help, too lazy)...use this:
Code:
dialog onservinfo {
  title "Whois"
  size -1 -1 207 173
  option dbu
  list 6, 3 3 200 150, size vsbar
  button "Close...", 1, 5 158 37 12, ok cancel
  box "", 2, 3 153 41 19
  box "", 3, 44 153 41 19
  button "Print...", 4, 46 158 37 12
}

ON *:DIALOG:onservinfo:sclick:4 {
  savebuf -o $dname 6 print.txt
  run notepad.exe /p print.txt
}