Bug 299588 [Forms] Widget disposed exception when closing shell from a FormText selection
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/widgets/FormText.java
* attribute. In addition, <b>width</b> and <b>height</b> attributes can
 * be used to force the dimensions of the control. If not used,
 * the preferred control size will be used.
 * </ul>
 * <p>
 * None of the elements can nest. For example, you cannot have <b>b </b> inside
 * a <b>span </b>. This was done to keep everything simple and transparent.
 * Since 3.1, an exception to this rule has been added to support nesting images
 * and text inside the hyperlink tag (<b>a</b>). Image enclosed in the
 * hyperlink tag acts as a hyperlink, can be clicked on and can accept and
 * render selection focus. When both text and image is enclosed, selection and
 * rendering will affect both as a single hyperlink.
 * </p>
 * <p>
 * Since 3.1, it is possible to select text. Text selection can be
 * programmatically accessed and also copied to clipboard. Non-textual objects
 * (images, controls etc.) in the selection range are ignored.
 * <p>
 * Care should be taken when using this control. Form text is not an HTML
 * browser and should not be treated as such. If you need complex formatting
 * capabilities, use Browser widget. If you need editing capabilities and
 * font/color styles of text segments is all you need, use StyleText widget.
 * Finally, if all you need is to wrap text, use SWT Label widget and create it
 * with SWT.WRAP style.
 * 
 * @see FormToolkit
 * @see TableWrapLayout
 * @since 3.0
 */
public class FormText extends Canvas {