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
private Hashtable resourceTable = new Hashtable();
	private IHyperlinkSegment entered;
	private IHyperlinkSegment armed;
	private boolean mouseFocus = false;
	private boolean controlFocusTransfer = false;
	private boolean inSelection = false;
	private SelectionData selData;
	private static final String INTERNAL_MENU = "__internal_menu__"; 
	private static final String CONTROL_KEY = "__segment__"; 
	private class FormTextLayout extends Layout implements ILayoutExtension {
		public FormTextLayout() {
		}
		public int computeMaximumWidth(Composite parent, boolean changed) {
			return computeSize(parent, SWT.DEFAULT, SWT.DEFAULT, changed).x;
		}
		public int computeMinimumWidth(Composite parent, boolean changed) {
			return computeSize(parent, 5, SWT.DEFAULT, true).x;
		}
		/*
		 * @see Layout#computeSize(Composite, int, int, boolean)
		 */
		public Point computeSize(Composite composite, int wHint, int hHint,
				boolean changed) {
			long start = 0;
			if (DEBUG_TEXT)
				start = System.currentTimeMillis();
			int innerWidth = wHint;
			if (innerWidth != SWT.DEFAULT)
				innerWidth -= marginWidth * 2;
			Point textSize = computeTextSize(innerWidth);