STEPS TO REPRODUCE:
1) Set Control Panel | Regional and Language Options | Regional Options tab | Standards and Formats locale choice to any of the following four Sun supported localizations -- Chinese (PRC), Chinese (Taiwan), Japanese or Korean.
2) Try to start a signed applet that will cause the Security Warning dialog to appear. The following page can be used (as it was for Sun bug#6379439),http://www.varju.ca/test/applet/.
The translated strings for the text in the topmost panel i.e., "The application's digital signature cannot be verified. Do you want to run the application?" and the bottommost panel i.e., "The digital signature cannot be verified by a trusted source. Only continue if you trust the origin of the application." should appear with valid glyphs (not missing glyph/square boxes) for the appropriate Chinese, Japanese and Korean translations.
The translated text in the top and bottommost panels in the dialog show square boxes. However, the translated text (for Name/Publisher/From, for the checkbox and label, and for the buttons) in the middle pane of the dialog displays correctly with the appropriate Chinese, Japanese and Korean glyphs.