Occasionally you'll want to use a shape as panel. Normally, shapes are simple graphic elements that do not allow photos to be dropped inside them, so you must convert a shape for use as a panel. To do this, simply select the shape and choose Format->Convert Shape To Panel.
Note: If the shape was a pre-defined shape, it is converted to an editable shape.
Once the conversion is complete the shape is drawn as a panel (with the normal "drop hint" in the center):