keep track of one per display:
  tk_priv(...)
    window
    posted
    focus
    relief
    cursor
    activeBg activeFg
    inMenuButton
    dragging x y
    selectMode
    buttons

fix button tracking
fix menu tracking
fix pie menu tracking

tk_mbUnpost needs argument to tell which display
tk_nextMenu needs argument to tell which display
tk_nextMenuEntry needs argument to tell which display

which display does "selection" work on???

fix c event focus code to keep focus in display instead of main window

added "focus -query window" form to find out focus on a particular display
