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
setLayout(new StatusLineLayout());
        fMessageLabel = new CLabel(this, SWT.NONE);
        
        
        
        
        
        fProgressIsVisible = false;
        fCancelEnabled = false;
        fToolBar = new ToolBar(this, SWT.FLAT);
        fCancelButton = new ToolItem(fToolBar, SWT.PUSH);
        fCancelButton.setImage(fgStopImage.createImage());
        fCancelButton.setToolTipText(JFaceResources
                .getString("Cancel_Current_Operation")); 
        fCancelButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                setCanceled(true);
            }
        });
        fCancelButton.addDisposeListener(new DisposeListener() {
            public void widgetDisposed(DisposeEvent e) {
                Image i = fCancelButton.getImage();
                if ((i != null) && (!i.isDisposed()))
                    i.dispose();
            }
        });
        
        
        fProgressBarComposite = new Composite(this, SWT.NONE);
        GridLayout layout = new GridLayout();