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
* 
     * @return <code>true</code> if it is alright to close this dialog, and
     *  <code>false</code> if it is not
     */
    private boolean okToClose() {
        if (activeRunningOperations > 0) {
            synchronized (this) {
                windowClosingDialog = createWizardClosingDialog();
            }
            windowClosingDialog.open();
            synchronized (this) {
                windowClosingDialog = null;
            }
            return false;
        }
        return wizard.performCancel();
    }
    /**
     * Restores the enabled/disabled state of the given control.
     *
     * @param w the control
     * @param h the map (key type: <code>String</code>, element type:
     *   <code>Boolean</code>)
     * @param key the key
     * @see #saveEnableStateAndSet
     */
    private void restoreEnableState(Control w, Map h, String key) {
        if (w != null) {
            Boolean b = (Boolean) h.get(key);
            if (b != null) {