I just tried creating sub-lists, but I didn't succeed anyhow.. How should it be done? Indenting list's members only really indents them. Where's the "demote" button or smth?

Right click on the paragraph and select paragraph properties. The right most tab shows the numbering and you can select 'level' there.

See also bug 207057 on bugs.kde.org

Um.. am I blind or what.. where is "Right click on the paragraph"? What paragraph? The item in the list? There's no paragraph properties in that menu - the closest thing I find to "paragraph properties" is "Format->Paragraph" that has "Bullets/Numbers" tab, but only "Display Levels" under that.

Any more tips?