[CopperWing]

Well, LibreOffice is not "copyleft" licensed. It is distributed under a joint of licenses: GNU Lesser GPL v3+ and Mozilla Public License v2. The latter is not "copyleft".

[mindcrime]

I could be wrong, but from what I remember, the MPL has generally been considered a "weak copyleft" license.

[CopperWing]

As far as the Wikipedia definition of it goes, yes it is a "weak copyleft", but that basically means that the license on code and patents is liberal, while license on trademarks is not. That is to prevent bottom feeders to take for example Firefox and LibreOffice, rebuild them with adware and malware and redistribute new installers as "Super Firefox", "LibreOffice Improved" or other misleading trademarks.