In order in Pencil2D to enable different components of Penny’s face to be manipulated in different ways, it is necessary to draw them as different lines, technically called ‘paths’.
When she opens her mouth, her jaw drops. If we look at the two components of her face, illustration at the bottom of page, we see that they are formed of a line with a cap in it. When filled the edge, in the gap is a straight line.
I understand that for animators brought up on bitmapped drawing, this idea might be seen as strange, but this is the way that vector drawing and animation packages operate.
The Pencil2D file for this aniation is Meet_Penny-2.pclx (518.7 KB)
The illustration below is a screen capture image of the parts of Penny, with the top of the head raised, so you can see the components of the head shape separated.
