Resizing the panel Gestionnaire des extensions makes the list of extensions disappear.
Steps to reproduce:
1. load LibreOffice
2. click Outils, Select Gestionnaire ...
3. Resize the form
Platform (if different from the browser):
Browser: Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko/20100101 Firefox/11.0
Thanks for your report.
Already reported (and fixed) as 'Bug 47963 - UI: Extension list shrinks and finally disappears on resizing window'.
(Bug-fix will be available in LibreOffice 3.5.3.)
*** This bug has been marked as a duplicate of bug 47963 ***