While talking to Prashant, the student working on the "Improve toolbars in
LibreOffice" GSoC project , and Kendy, we came across the idea to have a
separate style for some toolbars. The idea was to use small icons grouped
inside buttons, as in Spice of Design's Writer concept , Microsoft
Office 2007  (and Office for Mac), or iWork .
I suggested to have a per-toolbar setting of either large/small icons, with
the toolbars using small icons having the same height as those with large
icons (as in Spice of Design's concept ). The icon set for large icons
would be set separately from the one for small icons. (I would expect Tango
for large icons and Symbolic for small icons by default.)
The reasons for carrying out this change would be decreasing toolbar width,
making the association between related commands clearer, separating
contextual commands visually, and hopefully giving LibreOffice a nicer look.