All LibreOffice applications have the ability to insert comments. However, only Impress and Draw have a toolbar for this feature. Calc and Writer don't have a toolbar for it. In Impress or Draw you can enable the toolbar via "View"->"Toolbars"->"Comments". The toolbar is very handy and also looks nice. Why is the same toolbar not available in Calc and Writer? These applications have the same comment core functionality. Hence, I believe it should be very easy to enable the toolbar also in Calc and Writer.
In the EasyHacks wiki page an interesting alternative approach to a comments tool bar is described: Background: We have a great new 'notes' feature, but it is hard to turn this on and off. We have a beautiful design mockup (http://wiki.services.openoffice.org/wiki/Notes2_Design_NotesSidePane#Proposal_.22Notes_Ruler_Control.22) of how this could be done as an extension to the existing ruler code. The existing ruler code is (shared) in svx/source/dialog/svxruler.cxx and svx/inc/svx/ruler.hxx - and this builds on top of the svtools ruler: svtools/inc/ruler.hxx and svtools/source/control/ruler.cxx - see eg. Ruler::Paint there (and vcl's outdev.hxx for drawing methods). Source: http://wiki.documentfoundation.org/Development/Easy_Hacks_Complete_List
UX Comment: A note to this request - Impress/Draw notes have been created by a different author without proper UX support. When we've designed the notes for Writer, we tried to explicitly _avoid_ another toolbar. So the "issue" is indeed a feature. So, I recommend to remove the toolbar from Impress/Draw and add sufficient Notes handling in the Navigator of Impress/Draw/Calc.
@Christoph: I agree with your proposed solution. A "comments ruler control" will be a much better solution than another toolbar. What to do with this bug? Renaming it or marking it as "fixed-invalid" and opening a clean new bug entry for your idea?
Proposal in bug 38246 is superior to this one. Therefore, closing as duplicate. *** This bug has been marked as a duplicate of bug 38246 ***
Migrating Whiteboard tags to Keywords: (EasyHack) [NinjaEdit]