If you have upgraded from 1.90 to 8.05, and the styles on your dialog boxes (add link, attach file, etc) are missing, you may have dialogs that look like this:

...but should look like this!

If you're running AdBlock Plus, it could be the culprit. Look at the blockable items list (by hitting Ctrl-Shift-V or clicking on the ABP stop sign logo, and selecting "Open blockable items".

The CSS for the popup dialogs is blocked because it matches the pattern 'popup.css|' (the pipe sign, '|', means to not add a wildcard at the end of the rule). It's very easy to remove this. You can right-click the item and click "Add exception rule for item..." to unblock it specifically.

Adblock Plus will automatically enter the address to your own popup.css file into the dialog box for you.
If you want to remove it for a more general case (multiple DekiWiki installations), you can open the Adblock Plus preferences, and add a rule to exclude "@@popup.css|".

The "@@" syntax signifies an exception rule, rather than a blocking rule. (Learn more about Adblock Plus filters .)
This bug was fixed in SVN just after the release of 8.05.1.