Consider mapping right-click to erase or draw with a secondary color. MSPaint had this feature and it was ideal for "pushing around" pixels. I've sorely missed this functionality in most pixel art tools.
This is really nice. Much nicer than the plotter apps I've tried to use recently. Lots of attention given to UX details. I needed something like this with square cels recently. The best web app I could find was kind of terrible. You couldn't save, and it slowed to a crawl after a hundred pixels or so.
So when I was doing stuff with it, I realised I don't wanted to save in my palette all the color I used for the illustration. So add colors to the palette has to be a manual action from the user.
But Im open to suggestions, you're not the first and not the last to complain about it :) [some people find it extremely confusing]
A minor suggestion: give more buttons in the UI `pointer: cursor` and hover states; it will be easier to see when a click will actually do something (thinking in particular of the black bar of icons at the bottom of the page).
Hmm.. that's not working for me on a mac. I can select a single triangle? option/command + click would be quite convenient vs select each individual cell... since you could drag to erase.
Your ad blocker might need to be disabled. I also had the same problem, but it worked after adding an exception for the page in uBlockO (the extension icon did not indicate that anything was blocked, though).