Draggable Text

local text_objects = { --All of our text objects
  [1] = { --Layer by layer: it's necessary to do this in seqential order if we want to draw things correctly
    text = "Layer 1",
    color=colors.orange,
    x1=1,
    y =1
  },
  [2] = {
    text=" Layer 2",
    color=colors.blue,
    x1=1,
    y=2
  },
  [3] = {
    text= "Layer 3",
    color=colors.green,
    x1=1,
    y=3
  },
  [4] = {
    text="Layer 4",
    color=colors.cyan,
    x1=1,
    y=3
  }
}

local function draw() --The main draw function
  term.setBackgroundColor(colors.black)
  term.clear()
  for index=#text_objects, 1, -1 do --Start at 4, goto 1
    local ref=text_objects[index] --Our "pointer" to the text object
    ref.x2 = ref.x1+#ref.text --The rightermost boundary of the text object
    term.setBackgroundColor(ref.color)
    term.setCursorPos(ref.x1, ref.y)
    term.write(ref.text)
  end
end

local function checkClick(x,y) --Check if we have actually clicked on something
  for index=1, #text_objects do --We can start at 1 and goto 4 now because layer 1 is on top
    local ref=text_objects[index] --Our reference again
    if x>=ref.x1 and x<=ref.x2 and y==ref.y then --Check to see if the click is inside of the boundaries
      return index --If it is, then return the index
    end
  end
  return false --Looks like nothing matched. Return false
end

local function moveTextObject(index, clickX, dragX, dragY) --Move the text object to a new position
  local ref = text_objects[index]
  ref.x1 = ref.x1 + (dragX-clickX) --Make sure that we don't have jumping text objects!
  ref.y = dragY
end

local selector = {false} --All of the data about the "selected" text object
while true do
  draw() --Draw first so we can see what we're clicking
  local e = {os.pullEvent()}
  if e[1] == "mouse_click" then
    selector = {checkClick(e[3], e[4]), e[3]} --Get the data about the click and store it inside of selector
  elseif e[1] == "mouse_drag" then
    if selector[1] then
      moveTextObject(selector[1], selector[2], e[3], e[4]) --Move the text object if there selector[1] ~= false or nil
      selector[2] = e[3] --Since we've moved the text object, our old clickX will no longer apply so we have to set it to the dragX
    end
  end
end