I want create custom color picker by script, but i can't?

hi ! i like aseprite and it awesome work.
I want to customize a color window, but the current script is so weak, I can’t do it.

like this :

if i have one of them implement, i can do that :

  1. make a way to custom widget just like :
     local dlg = Dialog()
    dlg:custom{ id="xxxxxxxx",
                 onDraw=function(w,h, mouseStatus, keyStatus) .../*draw invoked*/..... end
  1. make way to create a timer :
  -- Prevent secondary creation
    if app.timer["timer 1"] == nil then 
        app.timer["timer 1"] = { ,
                onTick=function() ..../* maybe cross-thread operation */..... end, -- update each frame

in this way, i will create a window outside.