Hello Klaus,
System Font is specified here:
HKEY_LOCAL_MACHINE\System\GDI\SYSFNT
Users with Japanese o/s will see the message box correctly, I have tested it.
When it comes to system messages, the resident o/s overrides the Japanese
character codes, and hits the wrong code because the table of charcaters is
much larger for Japanese, finally showing nothing but squares.
Likewise, your French o/s overrides Japanese for Hai and Iie with Oui and No
using Tahoma font.
You could try and set MS Gothic in the above registry. Even if it works, you
will need to set Tahoma again to return to French.
It is reasonable to assume that European language users would not install
that large MS Gothic font for a short exotic experience, while Japanese users
have it in ROM anyway.
The labels look fine