When you define a style based on another one, you are not allowed to specify the character size as a percentage of the style you are basing on. The feature would be very useful, and supposedly it's simple to implement, since it's implemented in writer.
[This is an automated message.] This bug was filed before the changes to Bugzilla on 2011-10-16. Thus it started right out as NEW without ever being explicitly confirmed. The bug is changed to state NEEDINFO for this reason. To move this bug from NEEDINFO back to NEW please check if the bug still persists with the 3.5.0 beta1 or beta2 prereleases. Details on how to test the 3.5.0 beta1 can be found at: http://wiki.documentfoundation.org/QA/BugHunting_Session_3.5.0.-1 more detail on this bulk operation: http://nabble.documentfoundation.org/RFC-Operation-Spamzilla-tp3607474p3607474.html
in 3.5.0 not implemented yet, but in documentation written that it available
Just an update: Bodhi Moksha LibreOffice 5.0.2.2 Not implemented. Requesting developer input as I wonder if this might be an interesting easy hack.
It is implement in Version: 5.2.0.2 Build ID: a7567a46e5d2953c320b13eb88a3981c4f9bd1e0 CPU Threads: 4; OS Version: Windows 6.1; UI Render: default; Locale: de-DE (de_DE) So I set worksforme. It works correctly for font size in paragraph style. For font size in character styles it is correct in the file, but the UI does not adapt automatically. So you need to save and reload to see the change, if the size in the parent style is changed. But that is a bug and therefore needs a new bug report.