-- Send a message to the console
function msg(m)
    reaper.ShowConsoleMsg(tostring(m) .. "\n")
end

-- START HERE vvvvvvvvvvvvvvvvv
local track_str = ''
local retval

retval, track_str = reaper.GetProjExtState(0, '4PointCut', 'dst_track')
if retval > 0 then -- variable exists in rpp
    reaper.SetOnlyTrackSelected(reaper.BR_GetMediaTrackByGUID(0, track_str))
end