Bug 319509 [Viewers] Empty rows in CheckboxTableViewer with virtual table
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CheckboxTableViewer.java
* </p>
     *
     * @return the array of checked elements
     * @see #setCheckedElements
     */
    public Object[] getCheckedElements() {
        TableItem[] children = getTable().getItems();
        ArrayList v = new ArrayList(children.length);
        for (int i = 0; i < children.length; i++) {
            TableItem item = children[i];
            if (item.getChecked()) {
				v.add(item.getData());
			}
        }
        return v.toArray();
    }
    /**
     * Returns the grayed state of the given element.
     *
     * @param element the element
     * @return <code>true</code> if the element is grayed,
     *   and <code>false</code> if not grayed
     */
    public boolean getGrayed(Object element) {
        Widget widget = findItem(element);
        if (widget instanceof TableItem) {
            return ((TableItem) widget).getGrayed();
        }
        return false;
    }