We have introduced a "threshold" setting to eliminate an issue where white space was being left near the outline of your animation.
This means you can control the amount of fill and how aggressively the paint bucket will fill the lines. In other words, the fill threshold determines how far the fill will spread.
The threshold is found at the percentage beneath the color chosen for the bucket. To change this, press and hold on the "percentage icon" below the color picker and then move it up or down to increase/decrease.
If you are finding there is too much white space by the outline - simply increase the threshold until the fill is where you would like it to be.