In the very bottom left corner of the ArtRage window, in the tool selector, you'll see a preview of your stroke.
You can adjust the width of your stroke in several ways:
1) Click on the % indicator in the stroke preview area. A numeric box will pop up to let you enter a size percentage. Note that in ArtRage 2.11 you can enter numbers up to 500% size (if you need those REALLY big tools)
2) You can click and drag left or right in the stroke preview area to quickly size up or down.
3) You can click the + and - buttons to the left and right of the stroke preview to increase or decrease the stroke width slightly. (Clicking and holding those buttons does repeat on them).
4) On your keyboard, the right and left arrow keys increase and decrease the size of the tool. Hold <shift> down as well to increase and decrease in larger increments.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"