Bug 205923 [Viewers] Javadoc for setAllChecked() does not mention that only visible items are checked
setAllChecked which was added (by me) in 3.2 does not mention that all chidren must be visible for it to be checked (see setSubtreeChecked). We will have to leave it as it is API and does not expand the tree but I think we should deprecate it as setSubtreeChecked is really the only useful one. Boris what is your opinion?
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CheckboxTreeViewer.java
* Does not fire events to check state listeners.
     * @param element the item being checked
     * @param state a boolean indicating selection or deselection
     * @return boolean indicating success or failure.
     */
    public boolean setGrayChecked(Object element, boolean state) {
        Assert.isNotNull(element);
        Widget widget = internalExpand(element, false);
        if (widget instanceof TreeItem) {
            TreeItem item = (TreeItem) widget;
            item.setChecked(state);
            item.setGrayed(state);
            return true;
        }
        return false;
    }
    /**
     * Sets which elements are grayed in this viewer's tree.
     * The given list contains the elements that are to be grayed;
     * all other elements are to be ungrayed.
     * <p>
     * This method is typically used when restoring the interesting
     * state of a viewer captured by an earlier call to <code>getGrayedElements</code>.
     * </p>
     *
     * @param elements the array of grayed elements
     *
     * @see #getGrayedElements
     */
    public void setGrayedElements(Object[] elements) {