Interesting, though it doesn't seem to work with your user name? Is the star burst supposed to appear over the D? For me, it appears after the D; I'm using Google Chrome on Windows.
Hm. I've tested it under Linux with Firefox and Chrome. Let me check... yeah it does look different on Windows. And neither Firefox nor Chrome display my example diacritics at all.
The starburst character is a combining diacritical, so yes, it's supposed to surround the D. Then again, I kinda like how it comes out on Windows.
For the record, this is what it looks like to me:
I guess using combining diacriticals is out then, if they're not displaying correctly (everywhere).
It looks the same to me also, however, I made certain to configure support for all characters to appear in my environment. Many computer users do not.