Help with Erasing while dragging objects

[Sceyef]

so like, I have never liked animating in turing.
Here's my code. It's a simple drag-an-object program. Primitive, as the object centers on your cursor and stuff, but it works.

code:

var x, y, button, a, b : int a := 100 b := 100 var buttonpress : boolean := false setscreen ("offscreenonly") loop     mousewhere (x, y, button)     locate (1, 1)     if x > a - 50 and x < a + 50 and y > b - 50 and y < b + 50 then         if button = 1 then             buttonpress := true         else             buttonpress := false         end if     end if     if buttonpress = true then         a := x         b := y     end if     cls     drawfillbox (a - 50, b - 50, a + 50, b + 50, red)     View.Update end loop

Now here's what I need: I am currently erasing the red square with CLS. Later I need to add a background. How can I do that? Try it yourself, but when I attempt to put the usual identical object with colorbg, there are.. problems..? Even If I make the object bigger. It doesn't erase properly. :/

halp

[Zren]

Draw things that appear underneath first, then draw the thing on top second.

Turing:

cls % Begin drawing a new frame Draw.FillBox(0, 0, maxx, maxy, black) % Draw background Draw.Oval(x, y, r, r, red) % Draw foreground View.Update() % Done drawing the frame, show it on screen.