The extension OKDict-1.0.0.oxt [1] works fine with LibO 3.5.4/3.5.5.2 (on WinXP).
I cannot install OKDict-1.0.0.oxt in LibO 3.6.0.0.beta2 (via Extension Manager → Add…) due to the following error message:
[msci_uno bridge error] UNO type of C++ exception unknown: “CLuceneError”,
RTTI-name=".?AVCLuceneError@@"!
Helpful suggestions?
[1] OKDict - Kilargo
Please file a bug (http://wiki.documentfoundation.org/BugReport). Presumably this will be due to some problem with the extensions built-in help or LibreOffice’s parsing of that help
Which suggests that (if you desperately need to get it to work) if you unzipped OKDict-1.0.0.oxt and edited META-INF/manifest.xml and removed the lines…
<manifest:file-entry manifest:media-type="application/vnd.sun.star.help"
manifest:full-path="help"/>
and rezipped it up again that it might then work
Thanks–done → fdo#51572
Sorry, cannot tag as Answered. 
The modified extension has been installed without error message and works well
now (w/o help).
fdo#51572 has been fixed 
— ‘Accept Answer’ button still unavailable → fdo#51569 — marked as [SOLVED]
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mark this answer as correct works again.