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As you begin to drag a control from the Palette, you’ll see this 
icon, which means the control is not yet over a droppable area. When you reach an area on the canvas where dropping a control is allowed, the will change to this icon. You must drop controls into the body of the form; you can’t drop them into the toolbar nor can they be dropped below the Submit and Cancel buttons.
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You can drag/drop above, below, to the left and right of most controls. As you bring the control over the body of your form, the icon will change to one of the icons below:
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