Admin panel- Navigation menu manipulation:
(Add a new nav button)
unity/blog/entry/Admin_panel_Navigation_menu_manipulation

(From mrpowless's blog)

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Change navigation bar from 1 row to 2 row,
Settings/Advanced Settings
- Number of items per line in top menu. 0 - no breaking

change the number 0 to 6 or deppend on how many botton u want in one row
then click save