emacs 21.3.1 kill ring empty when pasting from other x window

[Randy Bush]

various -current systems, all less than a week since cvsup

if i 
  o start emacs 21.3.1
  o go to another window (say an emacs to a different host)
  o drag over some text (or mark and M-w)
  o go to the emacs mentioned in the first step
  o either yank or mouse-2

i get  "kill ring empty"

oh, and x-select-enable-clipboard is t

and emacs is randomly bombing out whining

  X protocol error: BadWindow (invalid Window parameter) on protocol request 38

randy