ESOUI SVN LibAddonMenu

--[[customData = {
        type = "custom",
        reference = "MyAddonCustomControl",     --unique name for your control to use as reference
        width = "full", --or "half" (optional)
}       ]]

local widgetVersion = 2
local LAM = LibStub("LibAddonMenu-2.0")
if not LAM:RegisterWidget("custom", widgetVersion) then return end

local wm = WINDOW_MANAGER

function LAMCreateControl.custom(parent, customData, controlName)
        local control = wm:CreateTopLevelWindow(controlName or customData.reference)
        control:SetResizeToFitDescendents(true)
        control:SetParent(parent.scroll)
        
        local isHalfWidth = customData.width == "half"
        if isHalfWidth then     --note these restrictions
                control:SetDimensionConstraints(250, 55, 250, 100)
                control:SetDimensions(250, 55)
        else
                control:SetDimensionConstraints(510, 30, 510, 100)
                control:SetDimensions(510, 30)
        end
        
        control.panel = parent.panel or parent  --if this is in a submenu, panel is its parent
        control.data = customData
        
        return control
end