-------------------------------------- MK Send All Note Offs on Track Changing (Defer)-----------------------

local r = reaper

function Main()
local trackx = track

            track = r.GetSelectedTrack(0, 0)

            if trackx ~= track then  
               r.Main_OnCommand(40345, 0) -- 
            end

         reaper.defer(Main)
end

Main()


-----------------------------------------------------------------------------------
-- Set ToolBar Button ON
function SetButtonON()
  local is_new_value, filename, sec, cmd, mode, resolution, val = r.get_action_context()
  r.SetToggleCommandState( sec, cmd, 1 ) -- Set ON
  r.RefreshToolbar2( sec, cmd )
end

-- Set ToolBar Button OFF
function SetButtonOFF()
  local is_new_value, filename, sec, cmd, mode, resolution, val = r.get_action_context()
  r.SetToggleCommandState( sec, cmd, 0 ) -- Set OFF
  r.RefreshToolbar2( sec, cmd )
end
-----------------------------------------------------------------------------------
SetButtonON()


function OnExit()
SetButtonOFF()
end

r.atexit(OnExit)