Bug 124202 [Field Assist] - decorated fields should not size the created control
The philosophy of DecoratedField is that the client creates the target control and accesses it with normal SWT coding. The decorated field manages the decorations but otherwise statys out of the way. This philosophy is violated when DecoratedField sets the width of the field to IDialogConstants.ENTRY_WIDTH. Sizing decisions should be made by the client of the decorated field, not the field itself.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/DecoratedField.java
*/
		if (decoration.getImage() == null) {
			formData.width = RESERVED_WIDTH;
			formData.height = 0;
		} else {
			formData.width = SWT.DEFAULT;
			formData.height = SWT.DEFAULT;
		}
		label.setImage(decDatas[i].decoration.getImage());
		label.setData(decDatas[i]);
		label.setVisible(!showOnFocus);
		label.setLayoutData(formData);
	}
	/**
	 * Get the control that is decorated by the receiver.
	 * 
	 * @return the Control decorated by the receiver, or <code>null</code> if
	 *         none has been created yet.
	 */
	public Control getControl() {
		return control;
	}
	/**
	 * Get the control that represents the decorated field. This composite
	 * should be used to lay out the field within its parent.
	 * 
	 * @return the Control that should be layed out in the field's parent's
	 *         layout. This is typically not the control itself, since
	 *         additional controls are used to represent the decorations.
	 */