I use photoshop and don't know anything about your program, but I use the pen tool to make a selection and then just delete everything inverse to the selection. Sometimes I'll lower the layer's opacity way down to make it transparent and then use the eraser by hand to erase everything. Create a layer mask (reveal all) and then use the black (darken) paintbrush on the mask to paint over what you want hidden. Then if you screw up, you can just reverse it using a white (lighten) paint brush. That way gives you more control than selecting and deleting or erasing huge chunks and having to undo if you mess up, and nothing is lost permanently. Oh, that was for Photoshop, I don't know anything about Pixelmator. Thanks to both of you. Despise the fact that you were talking about Photoshop I've still got it figured out a bit.