Drawing circles or ovals requires holding alt while clicking and dragging. On both Chromebook, and at least some versions of Gnu/Linux (I've had the problem using XFCE on both mint and crouton), this doesn't work, because the system already has that input set to do other things (messes with my window placement in Linux, and scrolls the window contents in Chromebook), intercepting that input so it can't reach the website. Using Alt for anything within a website is a bad idea in general, because nearly all browsers already use Alt for menus, and nearly every key combination using Alt is used for something on at least one of the major OSs. Why is a hotkey even needed for this? Just make circle/oval its own entry in the draw-tool drop-down list, like the polygon/line one, freehand, and text already are.