There are two types of elements that can be inserted in a drawing layer’s cell:
A layer can contain the two different elements, but only in different cells. You cannot put two symbols or a drawing and a symbol into the same cell.
If you want to mix bitmap images in your Drawing layers, you must first import your bitmap image as a symbol or turn it into a symbol and insert it in your Drawing layer by dragging the symbol cell there through the Timeline.
|•||Layers and Columns|
|•||Layer and Column Concepts|
|•||Advanced Column Types|