Bug 63223 Use null to clear message text instead of empty string
I200405200800 StatusLine in jface uses setMessage("") to clear the text while the documentation says you should uset setMessage(null) to clear the text. The code path is slightly different for "" versus null, but using null makes the intent of the caller clearer.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/StatusLine.java
* contributions.
                 * 
                 * The fix here is to draw the progress bar and
                 * cancel button off screen if they are not visible.
                 */
                if (w == fProgressBarComposite && !fProgressIsVisible
                        || w == fToolBar && !fCancelButtonIsVisible) {
                    w.setBounds(x + rect.width, y, ws[i], h);
                    continue;
                }
                w.setBounds(x, y, ws[i], h);
                if (ws[i] > 0)
                    x += ws[i] + GAP;
            }
        }
    }
    /**
     * Create a new StatusLine as a child of the given parent.
     */
    public StatusLine(Composite parent, int style) {
        super(parent, style);
        addDisposeListener(new DisposeListener() {
            public void widgetDisposed(DisposeEvent e) {
                handleDispose();
            }
        });