How to add GUI Properties in Jigloo for a custom control

I have a class that extends JPanel with the possiblitity to include a
background image. When I programmatically creates an object from this
class I supply a string containing the image filename to the
constructor. Jigloo seems to be using only default constructor without
parameters. So how can I from Jigloo:s GUI set which image to use? Is
it maybe possible to add a GUI Property for my custom component so
that it is seen in Jigloo:s list of properties?

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