When Resizeing a GUI it jumps weirdly

[0verKlutch (OverKlutch)]

when i drag the plus it jumps downwards

idk why is does this is it a issue with my screen

heres the code

wait(1)
local App = script.Parent
local Window = App.Window
local Over = App.Overlay

Window.Drag.MouseButton1Down:connect(function()
	Over.Visible = true
	local Move = Over.MouseMoved:connect(function(X,Y)
		local x = X-Window.AbsolutePosition.X-(Window.Drag.Size.X.Offset/2)
		local y = math.floor(((Y-(Window.Drag.Size.Y.Offset/2))/20)+0.5)*20
		if x < 400 then x = 400 end
		if y < 100 then y = 100 end
		Window.Size = UDim2.new(0,x,0,y)
	end)
	local Up
	local Leave
	Up = Over.MouseButton1Up:connect(function()
		Move:disconnect()
		Up:disconnect()
		Leave:disconnect()
		Over.Visible = false
	end)
	Leave = Over.MouseLeave:connect(function()
		Move:disconnect()
		Up:disconnect()
		Leave:disconnect()
		Over.Visible = false
	end)
end)

[Jexemie (Jeremie)]

I has to do maybe with the anchor points of the gui, try fixing those

[0verKlutch (OverKlutch)]

all the AnchorPoints are 0, 0 so should i change them to somthing else

[0verKlutch (OverKlutch)]

ok i fixed it by subtracting they y value by 13.6 so it will stay on the cursor

wait(1)
local App = script.Parent
local Window = App.Window
local Over = App.Overlay

Window.Drag.MouseButton1Down:connect(function()
	Over.Visible = true
	local Move = Over.MouseMoved:connect(function(X,Y)
		local x = X-Window.AbsolutePosition.X-(Window.Drag.Size.X.Offset/2)+10
		local y = math.floor(((Y-(Window.Drag.Size.Y.Offset/2))/20)-13.6)*20
		if x < 400 then x = 400 end
		if y < 100 then y = 100 end
		Window.Size = UDim2.new(0,x,0,y)
	end)
	local Up
	local Leave
	Up = Over.MouseButton1Up:connect(function()
		Move:disconnect()
		Up:disconnect()
		Leave:disconnect()
		Over.Visible = false
	end)
	Leave = Over.MouseLeave:connect(function()
		Move:disconnect()
		Up:disconnect()
		Leave:disconnect()
		Over.Visible = false
	end)
end)

so if anyone else is having this problem here is the code and all you do is subtracting or adding till it looks nice