You draw and paint using the mouse. It's left mouse only with drawing color being opposite of color below mouse pointer. Might seem a bit strange if you're used to using both left and right mouse buttons, but I'm sure you'll get the hang of it. Many other Flash utilities out there get by with exactly the same.
At the right are a few buttons. Double is a switch between single pen drawing and mirror around vertical center.
The pattern string area is continuously updated. The clipboard is updated automatically too. Anything you've just drawn can be pasted right away into Classic99 or your source text editor.
You can also enter values if you want to. The tabulator key should activitate the input field (beside other options), and then Delete will clear the field for pasting (if that's what you want). Any other editing will do too. You can even paste strings like this
>0028, >0044, >3800
>1038, >7CD6, >FE28, >4482