Bug 182190 [StatusHandling] [Wizards] getControl assert on wizard page has no message
M6 If you forget to set the control on your wizard page our assert gives no feedback. We need an error message.
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
* Method declared on IWizardContainer.
     */
    public void updateMessage() {
        if (currentPage == null) {
			return;
		}
        pageMessage = currentPage.getMessage();
        if (pageMessage != null && currentPage instanceof IMessageProvider) {
			pageMessageType = ((IMessageProvider) currentPage).getMessageType();
		} else {
			pageMessageType = IMessageProvider.NONE;
		}
        if (pageMessage == null) {
			setMessage(pageDescription);
		} else {
			setMessage(pageMessage, pageMessageType);
		}
        setErrorMessage(currentPage.getErrorMessage());
    }
    /**
     * Changes the shell size to the given size, ensuring that
     * it is no larger than the display bounds.
     * 
     * @param width the shell width
     * @param height the shell height
     */
    private void setShellSize(int width, int height) {
        Rectangle size = getShell().getBounds();
        size.height = height;
        size.width = width;