Any chance to customize the tab-icons (lock, etc.)?
None?
Yes, I guess there is none. Maybe possible with ResourceHacker, unexpected results and missing future-proofness included.
Don't use ResourceHacker or similar tools on the Opus binaries, unless you want Opus to stop working.
No, I would like to change them in an "offical" way.
Maybe such icons could be included into the iconset in future version (they seem to be smaller, but that could be solved in the xml e.g. using an own size).
The reason why I asked is because it breaks with the design when using non-default set (I'm actually working on a complete iconset including default and additional icons, that's why I asked).