Nicolas

-- This code is pretty ugly but hopefully it will be useful to you.
local width, height = ScrW(), ScrH()
local aspect = 9/16
local showoutline = true
local function ScrW()
    return width
end
local function ScrH()
    return height
end
local window, slider = vgui.Create("DFrame")
window:SetSize(200, 150)
window:Center()
window:MakePopup()
window:SetScreenLock(true)
window:SetTitle("Nicolas")
function window:OnClose()
    hook.Remove("HUDPaint", "nicolas")
end
local combo, aspectcombo = vgui.Create("DComboBox", window)
combo:DockMargin(0, 4, 0, 0)
combo:Dock(BOTTOM)
combo:AddChoice("640 x 480 (4:3)", {640, 480, 1})
combo:AddChoice("1280 x 1024 (5:4)", {640, 480, 2})
combo:AddChoice("1280 x 720 (16:9)", {1280, 720, 3})
combo:AddChoice("1920 x 1080 (16:9)", {1920, 1080, 3})
combo:AddChoice("1680 x 1050 (16:10)", {1920, 1080, 4})
function combo:OnSelect(i, v, d)
    aspectcombo:ChooseOptionID(d[3])
    slider:SetValue(d[1])
end
aspectcombo = vgui.Create("DComboBox", window)
aspectcombo:DockMargin(0, 4, 0, 0)
aspectcombo:Dock(BOTTOM)
aspectcombo:AddChoice("4:3", 3/4)
aspectcombo:AddChoice("5:4", 4/5)
aspectcombo:AddChoice("16:9", 9/16)
aspectcombo:AddChoice("16:10", 10/16)
function aspectcombo:OnSelect(i, v, d)
    aspect = tonumber(d)
    slider:OnValueChanged(width)
end
slider = vgui.Create("DNumSlider", window)
slider:Dock(FILL)
slider:SetMin(0)
slider:SetMax(width)
slider:SetDecimals(0)
function slider:OnValueChanged(v)
    width = v
    height = aspect*v
    self:SetText(string.format("%u x %u", ScrW(), ScrH()))
end
aspectcombo:ChooseOptionID(3)
combo:ChooseOptionID(3)

local check = vgui.Create("DCheckBoxLabel", window)
check:DockMargin(0, 4, 0, 0)
check:Dock(BOTTOM)
check:SetText("Show outline")
check:SetChecked(showoutline)
function check:OnChange(v)
    showoutline = v
end

-- Your code here
hook.Add("HUDPaint", "nicolas", function()
    surface.SetDrawColor(31, 0, 0, 95)
    surface.DrawRect(0, 0, width, height)
    if showoutline then
        surface.SetDrawColor(0, 0, 0, 255)
        surface.DrawOutlinedRect(1, 1, width-2, height-2)
        surface.DrawOutlinedRect(-1, -1, width+2, height+2)
        surface.SetDrawColor(255, 255, 255, 255)
        surface.DrawOutlinedRect(0, 0, width, height)
    end

    -- Your code here
end)