I now got my fullscreen mode working: Greenfoot Full Screen Demo But there is another problem now (could it be any different?). Somehow the application frame seems to get blocked. Unfortunately I don't know much about the security using applets. Does anyone know why exactly the frame is blocked? Or does anyone know how to fix this?

Check the stack trace: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "exitVM.0") at java.security.AccessControlContext.checkPermission(AccessControlContext.java:366) at java.security.AccessController.checkPermission(AccessController.java:560) at java.lang.SecurityManager.checkPermission(SecurityManager.java:549) at java.lang.SecurityManager.checkExit(SecurityManager.java:761) at javax.swing.JFrame.setDefaultCloseOperation(JFrame.java:394) at FullScreenWindow.<init>(FullScreenWindow.java:72) at FullScreenWorld.createFullScreenWindow(FullScreenWorld.java:165) at FullScreenWorld.<init>(FullScreenWorld.java:115) at ExampleWorld.<init>(ExampleWorld.java:13) at InitialisingWorld.act(InitialisingWorld.java:32) at greenfoot.core.Simulation.actWorld(Simulation.java:574) at greenfoot.core.Simulation.runOneLoop(Simulation.java:509) at greenfoot.core.Simulation.runContent(Simulation.java:215) at greenfoot.core.Simulation.run(Simulation.java:205) It looks like you're setting the close operation for the frame to "exit". An applet isn't allowed to exit the VM, so this causes an exception.

Oh that sounds like it's pretty easy to fix. Thank you very much davmac. But I still got one question: Where can I get this stack trace? I never find it when I run a jar file or a applet on the webside.

I now could fix some problems with the stack trace but now I again got a problem where I need help. The stack trace says: java.lang.NoClassDefFoundError: FullScreenWorld$1CursorDisappear at FullScreenWorld.manageCursor(FullScreenWorld.java:283) at FullScreenWorld.<init>(FullScreenWorld.java:117) at ExampleWorld.<init>(ExampleWorld.java:13) at InitialisingWorld.act(InitialisingWorld.java:32) at greenfoot.core.Simulation.actWorld(Simulation.java:574) at greenfoot.core.Simulation.runOneLoop(Simulation.java:509) at greenfoot.core.Simulation.runContent(Simulation.java:215) at greenfoot.core.Simulation.run(Simulation.java:205) Caused by: java.lang.ClassNotFoundException: FullScreenWorld$1CursorDisappear at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 8 more The problem occours because the class is not found. The class that is not found is declared locally. So my question: Are local classes not uploaded to the webside? Because offline everything works fine.

The local class is in the jar file, but it is incorrectly named as "FullScreenWorld$1cursorDisappear.class" (with a lower-case 'c' in 'cursor'). I guess you're on a system with a case-insensitive file system; you probably create the class initially with the wrong name, and then changed it. To fix the problem, just rename the file within your scenario manually (or delete it and re-compile) before exporting again.

Ok I'll try that. Thanks davmac.

The next problem: java.security.AccessControlException: access denied ("java.awt.AWTPermission" "watchMousePointer") at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at sun.plugin2.applet.AWTAppletSecurityManager.checkPermission(Unknown Source) at java.awt.MouseInfo.getPointerInfo(Unknown Source) at FullScreenMouseInfo.<init>(FullScreenMouseInfo.java:21) at FullScreenWindow.getMouseInfo(FullScreenWindow.java:158) at FullScreenWorld$1CursorDisappear.<init>(FullScreenWorld.java:256) at FullScreenWorld.manageCursor(FullScreenWorld.java:283) at FullScreenWorld.<init>(FullScreenWorld.java:117) at ExampleWorld.<init>(ExampleWorld.java:13) at InitialisingWorld.act(InitialisingWorld.java:32) at greenfoot.core.Simulation.actWorld(Simulation.java:574) at greenfoot.core.Simulation.runOneLoop(Simulation.java:509) at greenfoot.core.Simulation.runContent(Simulation.java:215) at greenfoot.core.Simulation.run(Simulation.java:205) Sounds like I'm not allowed to check the mouse state. Any ideas how to fix this?

I am just using mouseListeners. The stack trace says that there is a problem while creating a CursorDisappear object. This object has a field which is a FullScreenMouseInfo object. And while initialising this object there seems to be an access problem. The FullScreenMouseInfo object is only a interpreter for mouseEvent objects. A mouseListener sends the MouseEvents to the fullscreenwindow where they are interpreted with a FullScreenMouseInfo object. So I am just using a mouseListener. I don't get why this isn't working. Because again offline everything works perfectly.

The stack trace shows that you are calling "java.awt.MouseInfo.getPointerInfo()". This is not the same as using a mouse listener. The events passed to the mouse listener contain the mouse pointer location and button state.

Hallelujah!!!!!!!!!! I got it working. Thank you very much for all the help and all the time you invested. I think the result is realy good. May you have a look here.