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
FieldDecoration decoration;
		Label label;
		FormData data;
		boolean showOnFocus;
		boolean visible = true;
		/**
		 * Create a decoration data representing the specified decoration, using
		 * the specified label and form data for its representation.
		 * 
		 * @param decoration
		 *            the decoration whose data is kept.
		 * @param label
		 *            the label used to represent the decoration.
		 * @param formData
		 *            the form data used to attach the decoration to its field.
		 * @param showOnFocus
		 *            a boolean specifying whether the decoration should only be