Bug 162140 [Progress] Be more resilient to null args in StatusLine's progress monitor
bundles/org.eclipse.jface/src/org/eclipse/jface/action/StatusLine.java
* a direct effect on the layout because it will make a cancel button visible.
     *  
     * @param enabled <code>true</true> if cancel should be enabled
     */
    public void setCancelEnabled(boolean enabled) {
        fCancelEnabled = enabled;
        if (fProgressIsVisible && !fCancelButtonIsVisible && enabled) {
            showButton();
            layout();
        }
        if (fCancelButton != null && !fCancelButton.isDisposed()) {
			fCancelButton.setEnabled(enabled);
		}
    }
    /**
     * Sets the error message text to be displayed on the status line.
     * The image on the status line is cleared.
     * 
     * @param message the error message, or <code>null</code> for no error message
     */
    public void setErrorMessage(String message) {
        setErrorMessage(null, message);
    }
    /**
     * Sets an image and error message text to be displayed on the status line.
     * 
     * @param image the image to use, or <code>null</code> for no image
     * @param message the error message, or <code>null</code> for no error message
     */
    public void setErrorMessage(Image image, String message) {