When an signed applet is canceled (not accepting the certificate), the grey rectangle does not repaint itself correctly.

This is reproducible with both the old plugin and new plugin in Firefox and IE.

To reproduce:
- Open a web browser
- Open 2 tabs
- In the second tab, go to http://juibrowser.sf.net/demo.html
- *Immediately*, switch to the first tab before the security dialog shows.
- Click "Cancel" when being prompted
- Click the 2nd tab and observes that the grey rectangle is painting with the first tabs cliped image.