select pane that doesn't wrap.

select_pane.sh

#!/usr/bin/env bash

pane_at_edge() {
  direction=$1

  case "$direction" in
     "U") 
       coord='top'
       op='<='
     ;;
     "D")
       coord='bottom'
       op='>='
     ;;
     "L")
       coord='left'
       op='<='
     ;;
     "R")
       coord='right'
       op='>='
     ;;
  esac

  cmd="#{pane_id}:#{pane_$coord}:#{?pane_active,_active_,_no_}"
  panes=$(tmux list-panes -F "$cmd")
  active_pane=$(echo "$panes" | grep _active_)
  active_pane_id=$(echo "$active_pane" | cut -d: -f1)
  active_coord=$(echo "$active_pane" | cut -d: -f2)
  coords=$(echo "$panes" | cut -d: -f2)

  if [ "$op" == ">=" ]; then
    test_coord=$(echo "$coords" | sort -nr | head -n1)
    at_edge=$(( active_coord >= test_coord ? 1 : 0 ))
  else
    test_coord=$(echo "$coords" | sort -n | head -n1)
    at_edge=$(( active_coord <= test_coord ? 1 : 0 ))
  fi;
  echo $at_edge
}

select_pane_no_wrap() {
  direction=$1
  at_edge=$(pane_at_edge $direction)
  if [ "$at_edge" = 0 ] ; then
    tmux select-pane "-$direction"
  else
    :
  fi
}

echo "U" $(pane_at_edge "U")
echo "D" $(pane_at_edge "D")
echo "L" $(pane_at_edge "L")
echo "R" $(pane_at_edge "R")

echo "R" $(select_pane_no_wrap "L")