Before you draw and paint in Flash, it is important to understand how drawing, painting, and modifying shapes can affect other shapes on the same layer. When you draw a line across another line or painted shape, the line you draw acts like a knife and divides the other line or shape it crosses into separate segments. Furthermore, the drawn line itself is divided into segments, as shown in this illustration. You can select, move, and reshape each segment individually.
A fill; the fill with a line drawn through it; and the two fills and three line segments created by segmentation
When you paint on top of shapes and lines, the portion underneath is replaced by whatever is on top. Paint of the same color merges together. Paint of different colors remains distinct. Use these features to create masks, cutouts, and other negative images. For example, the leaf cutout below was made by moving the ungrouped leaf image onto the red shape, deselecting the leaf, and then moving the leaf away from the red shape.
To avoid inadvertently altering shapes and lines, group them or use layers to separate them. See Grouping objects and Layers overview.