Revert "More toolbar customization and related fixes."

This reverts commit a36480e2a128e32dc20369d57d85a486dec2dd81.
Revert "Reorganized and renamed the menus on the main menu bar."

This reverts commit 16c6d126fbf95812e07932086905df9977103348.
Revert "More work for 2-row header in notebook UI."

This reverts commit df6bc1925d39d858f6df233e02a0babe78f96eb7.
Reverting some changes to the toolbar, before making another attempt at laying these toolbars out nicely.