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
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Layout;
import org.eclipse.swt.widgets.ToolBar;
import org.eclipse.swt.widgets.ToolItem;
/**
 * A StatusLine control is a SWT Composite with a horizontal layout which hosts
 * a number of status indication controls.
 * Typically it is situated below the content area of the window.
 * <p>
 * By default a StatusLine has two predefined status controls: a MessageLine and a
 * ProgressIndicator and it provides API for easy access.
 * </p>
 * <p>
 * This is an internal class, not intended to be used outside the JFace framework.
 * </p>
 */
class StatusLine extends Composite implements IProgressMonitor {
    
    public static final int GAP = 3;