Embedding dialog and NPE when loading an applet the first time

It is noticed in jre8u20, when invoking most, if not all, applets the first time, there is a NPE related to the embedding dialog type. NPE shown in java console due to either Dialog type is not candidate for embedding or Embedding dialogs not enabled in Configuration.

The NPE does not show if you run the same applet again. To make it re-appear again, javaws -uninstall to clean the deployment cache

The issue is a regression since jre8u20-b13

*** Test Configurations:
- x86 Win 7
- All browser
- jre 8u20-b16

*** Steps to reproduce:
0) Install jre 8u20-b16
1) Enable tracing, java console
2) Use any browser to load java.com verification appelt
http://java.com/en/download/installed.jsp
3) Accept to run at the security dialog

If you find the follow NPE from java console, the issue is reproducible:
Dialog type is not candidate for embedding
java.lang.NullPointerException
at sun.awt.windows.WWindowPeer.getActiveWindowHandles(Unknown Source)
at sun.awt.windows.WToolkit.eventLoop(Native Method)
at sun.awt.windows.WToolkit.run(Unknown Source)


- For other unsigned applets from the web using ESL to run, the same NPE from java console
but for Embedding dialogs not enabled in Configuration


The issue does not occur if using 8u20-b12 or earlier build