Select multiple lines by pressing Shift while clicking on a line.
Dissolve start controls at what time in the morph the points near the selected lines should start changing colour. Before it starts changing colour only the colour values of the first image are used.
Dissolve stop controls at what time in the morph the points near the selected lines should finish changing colour. After it has finished changing colours only the colours of the last image are used.
Start point begin move controls at what time in the first point (drawn as a green dot) starts moving.
Start point stop move controls at what time in the first point (drawn as a green dot) stops moving.
End point begin move controls at what time in the last point (drawn as a blue dot) starts moving.
End point stop move controls at what time in the last point (drawn as a blue dot) stops moving.
If the lines are connected, then the points between the first and the last control point will have values inbetweened.