In new template manager, introduced in 4.0.0, selecting template in main window causes button bar to change. It gives new buttons, like "Edit", "Properties" etc. Unfortunately, it also removes search button and "gear button". Currently to search for template users must deselect item, most likely by going one directory up. I can not see any rationale for this. Why users should not search for templates after selecting one? I strongly believe that search button and "gear button" should be always present by right side of button bar.
I can confirm this behavior using Linux Mint 14 x64 and LibreOffice 4.0.0.3 rc3. I think it'll indeed be useful to search and resort the list again, also when you have a template selected. Therefore I mark this as NEW. @Cedric: the template manager is one of your children ;-). Therefore I put you in CC.
Fixed by commit http://cgit.freedesktop.org/libreoffice/core/commit/?id=f7c47eddc9d736ec59772106cada2e4adde9c82c on master