embedding plots get triggered during long brush strokes

I noticed that sometimes when painting with long brush strokes, the plot update gets triggered.

To reproduce, I think it's something like:
1. paint one stroke and release the mouse button
2. In less than one second (the debounce duration), start painting again
3. if you don't complete the paint stroke before 1s after (1), I think the drawing gets triggered.

We can consider using the `labels_update` event instead. I _think_ that gets triggered during the draw of the paint stroke.