The DOCK attribute is restricted to a small set of gadgets only, and is principally aimed at the Frame gadget. It is quite difficult to use, but allows you to DOCK a frame to the LEFT or RIGHT or TOP or BOTTOM edge of its container (frame or form) or to DOCK FILL, i.e. dock to all to all edges simultaneously. The default is DOCK NONE.

View, Alpha, Paragraph, Textpane and Container gadgets support DOCK FILL only.