gistfile1.lua

-- optionsTable
local frameStacks = {
	["main"] = {
		frames = {},
		firstPos = { "RIGHT", UIParent, "RIGHT", -65, -85 },
		nextPos = { "BOTTOM", "TOP", 0, 15 },
		nextColPos = { "BOTTOMRIGHT", "BOTTOMLEFT", -15, 0 },
	},
}

-- This anchors one frame in its stack
local function stackAnchorSingle(frame)
	local stack = frame.stack
	local frames = stack.frames

	local height = frame:GetHeight() / frame:GetEffectiveScale()
	local uiHeight = UIParent:GetHeight() / UIParent:GetEffectiveScale()

	frame:ClearAllPoints()
	frame.beginsCol = nil

	local searchBeginning
	for i=frame.stackPos-1, 1, -1 do
		local prev = frames[i]

		if(prev:IsShown()) then
			if(searchBeginning) then
				if(prev.beginsCol) then
					-- This frame begins a new column, anchor next to it!
					local a,b,c,d = unpack(stack.nextColPos)
					frame.beginsRow = true
					return frame:SetPoint(a, prev, b,c,d)
				end
			elseif(prev:GetTop() / prev:GetEffectiveScale() + height > uiHeight) then
				-- Our frame wouldn't fit on this column, create a new one
				searchBeginning = true
			else
				-- Just place on column
				local a,b,c,d = unpack(stack.nextPos)
				return frame:SetPoint(a, prev, b,c,d)
			end
		end
	end

	-- No previous frame found? Be the first then!
	frame:SetPoint(unpack(stack.firstPos))
	frame.beginsCol = true
end

-- This anchors a frame and the following ones
local function stackAnchorFrame(frame)
	stackAnchorSingle(frame)

	for i=frame.stackPos+1, #frameStacks[stackname].frames do
		stackAnchorSingle(frame)
	end
end

-- Anchors all frames in the stack
function stackAnchorAll(stackName)
	for i,frame in ipairs(frameStacks[stackName].frames) do
		stackAnchorSingle(frame)
	end
end

-- Adds a frame to the stack
function addToStack(frame, stackName)
	local stack = frameStacks[stackName]

	table.insert(stack.frames, frame)
	frame.stack = stack
	frame.stackPos = #stack.frames
end

gistfile2.lua

addToStack(MyFrame, "main")

MyFrame:SetScript("OnShow", stackAnchorFrame)
MyFrame:SetScript("OnHide", stackAnchorFrame)