Bug 143659 [Accessibility] Press Tab key will cause eclipse crash when focus isn't on any report item in Editor view
Press Tab key will cause eclipse crash when focus isn't on any report item in Editor view Steps to reproduce: 1. New a report 2. Click the blank area in Layout of Editor view 3. Press Tab key Expected result: Something in layout will get focus Actual result: Eclipse crashed
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/editors/parts/ReportFocusTraverseManager.java
*  
			 * If the focused sibling has children, traverse to its leftmost child.
			 * If the focused sibling has no children, traverse to the sibling
			 * to its right.
			 * If there is no sibling to the right, go up the tree until a node
			 * with untraversed siblings is found.
			 */
			List siblings = parent.getChildren();
			int siblingPos = siblings.indexOf(nextFocusOwner);		
			if (siblingPos < siblings.size() - 1) {
				nextFocusOwner = ((IFigure)(siblings.get(siblingPos + 1)));
				if (isFocusEligible(nextFocusOwner))
					found = true;
			} else {
				nextFocusOwner = ((IFigure)(siblings.get(0)));
				if (isFocusEligible(nextFocusOwner))
					found = true;
				
			}		
		}
		return nextFocusOwner;
	}
	/**
	 * Returns the IFigure that will receive focus upon a 'shift-tab' traverse event.
	 * 
	 * @param root The {@link LightweightSystem LightweightSystem's} root figure
	 * @param focusOwner The IFigure who currently owns focus 
	 * @return the previous focusable figure
	 */
	public IFigure getPreviousFocusableFigureInSameOrder(IFigure root, IFigure focusOwner) {