[Lazarus]

Thanks, but I'm 99% sure It's not the mouse handling, I'm half as sure as that that it's the mouse_cap state not getting through to the script.

Here's a script that's been bodged-up from one of Schwa's tests he posted in the early days...

gfx.init("Click test",200,200)
reaper.atexit(gfx.quit)

---- generic mouse handling ----

mouse={}

function OnMouseDown()
  reaper.ShowConsoleMsg("OnMouseDown\n")
  mouse.down=true ; mouse.capcnt=0
  mouse.ox,mouse.oy=gfx.mouse_x,gfx.mouse_y
end

function OnMouseDoubleClick()
  reaper.ShowConsoleMsg("OnMouseDoubleClick\n")
end

function OnMouseMove()
   
  mouse.lx,mouse.ly=gfx.mouse_x,gfx.mouse_y
  mouse.capcnt=mouse.capcnt+1
end

function OnMouseUp()
  reaper.ShowConsoleMsg("OnMouseUp\n")
  mouse.down=false
  mouse.uptime=os.clock()
end

---- runloop ----

function runloop()
  gfx.clear=0xFF0000
  
  gfx.r=1
  gfx.rect(0,0,200,200)
  if gfx.mouse_cap&1 == 1 then
    if not mouse.down then
      OnMouseDown()      
      if mouse.uptime and os.clock()-mouse.uptime < 0.25 then 
        OnMouseDoubleClick()
      end
    elseif gfx.mouse_x ~= mouse.lx or gfx.mouse_y ~= mouse.ly then
      OnMouseMove() 
    end
  elseif mouse.down then 
    OnMouseUp() 
  end
  gfx.update() 
  local c=gfx.getchar()
  if c >= 0 and c ~= 27 then reaper.defer(runloop) end
end

reaper.defer(runloop)

If people can run they'll see that although Reaper controls respond correctly to tapping touchpads and touching the screen, the ReaScript code does not.