paint program

I have come across a few tutorials on creating a simple paint program. The problem is, they don't allow a solid line to be painted even with the mouse moving at medium speed.

Here is an example of how it is usually implimented:
(Super simplified)

Graphics 500,500,16,2

SetBuffer BackBuffer()

ClsColor 255,255,255

Color 0,0,0

Cls

While Not KeyDown(1)

If MouseDown(1) Oval MouseX() - 5,MouseY() - 5,10,10

Flip
Wend

End

I was wondering if anyone knows a better way to do this.
thanks.