FULL PRODUCT VERSION :
JDK 9 b54, JDK 8u40 b26, JDK 8u20 b26

ADDITIONAL OS VERSION INFORMATION :
OS X 10.9.5, 10.9.1

A DESCRIPTION OF THE PROBLEM :
Java Console GUI elements like "Clear", "Copy", "Close" buttons, scroll bars, text area are irresponsive to user actions on OS X, when an applet is loaded either in Firefox or Safari web browser.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Install JRE 9 or JRE 8 on the host.
2. Go to "Java Control Panel -> Advanced" and:

    a. Switch on the options: "Enable tracing", "Enable logging", "Show applet lifecycle exceptions" in "Debugging" group.
    b. Set "Java console" to "Show console".

3. Load any Java applet in Firefox or Safari web browser. For example, a demo applet from "The Java Tutorials" web site accessible at the next URL. http://docs.oracle.com/javase/tutorial/deployment/applet/index.html
4. Click "Clear", or "Copy", or "Close" button in the shown Java Console dialog. If the expected action does not occur, the bug is reproduced.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
When the bug occurs an exception with the following call stack is logged in OS X "Console" application.

java.lang.NullPointerException
        at sun.plugin2.applet.Plugin2Manager.getPlugin2ManagerList(Unknown Source)
        at sun.plugin2.applet.Plugin2Manager.getFromAppContext(Unknown Source)
        at sun.plugin2.applet.Plugin2Manager.getCurrentManager(Unknown Source)
        at sun.plugin2.applet.Applet2BrowserService.getContext(Unknown Source)
        at sun.plugin2.applet.Applet2BrowserService.isConsoleIconifiedOnClose(Unknown Source)
        at sun.plugin2.applet.Plugin2ConsoleController.isIconifiedOnClose(Unknown Source)
        at com.sun.deploy.uitoolkit.impl.awt.ui.SwingConsoleWindow.isVisible(Unknown Source)
        at sun.lwawt.LWWindowPeer.focusAllowedFor(LWWindowPeer.java:1221)
        at sun.lwawt.LWWindowPeer.requestWindowFocus(LWWindowPeer.java:1159)
        at sun.lwawt.LWWindowPeer.notifyMouseEvent(LWWindowPeer.java:807)
        at sun.lwawt.macosx.CPlatformResponder.handleMouseEvent(CPlatformResponder.java:83)
        at sun.lwawt.macosx.CPlatformView.deliverMouseEvent(CPlatformView.java:197)