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
*/
	private void controlFocusGained() {
		for (int i = 0; i < DECORATION_SLOTS; i++) {
			if (decDatas[i] != null && decDatas[i].showOnFocus)
				setVisible(decDatas[i], true);
		}
	}
	/*
	 * The target control lost focus. Any decorations that should show only when
	 * they have the focus should be hidden here.
	 */
	private void controlFocusLost() {
		for (int i = 0; i < DECORATION_SLOTS; i++) {
			if (decDatas[i] != null && decDatas[i].showOnFocus)
				setVisible(decDatas[i], false);
		}
	}
	/**
	 * Show the specified decoration. This message has no effect if the
	 * decoration is already showing, or was not already added to the field
	 * using <code>addFieldDecoration</code>.
	 * 
	 * @param decoration
	 *            the decoration to be shown.
	 */
	public void showDecoration(FieldDecoration decoration) {
		FieldDecorationData data = getDecorationData(decoration);
		if (data == null)
			return;