I have created this applet, It moves mouse to 1000 pos on screen. It works as application but it does not work in applet. I have created signed applet but still it wont move
I've checked the source-code from Robot. And I think you have to add in the constructor a ScreenDevice.
Signing alone won't give your Applet any permissions. You need to grant the createRobot permission to your Applet.
createRobot
Check the security tutorials for more details.