Acrobat 3 contained two sets of three toolbar buttons; Page Mode and Page View.

Page Mode contained the following three buttons:

None, Show Bookmarks and Show Thumbnails

Page View contained the following three buttons:

Fit Page, Fit Visible & Zoom 100%

To save space on the toolbar; TriState was built to convert groups of three toolbar buttons into single tri-state buttons.

This source demonstrates the use of the following notifications:




In addition, it also demonstrates adding and removing toolbar buttons.