It would be useful to have an uno command for inserting a horizontal line in Writer Web, rather than users having to guess that in order to create it, they have to set the paragraph style to horizontal line.
Indeed -> NEW.
There was an uno command for this in 3.6.7 - .uno:InsertGraphicRuler - so it would be good to track down where it was removed so that the commit can be reverted.
So Matthew tracked it down - http://cgit.freedesktop.org/libreoffice/core/commit/?id=3be15a051444d4d2f805d95e27831d5f466c1497
Dont think there is a need to bring back the full dialog part of it, as those are just long horizontal images being inserted.
Horizontal line was a paragraph style and this wasnt removed from LO and can be used with .uno:StyleApply?Style:string=Horizontal Line&FamilyName:string=ParagraphStyles