Hi Jack,

There actually isn't any programatic access to the toolwindow toolbars,
such as the one in solution explorer. Typically, the toolbar items just
invoke a specific command, so you could simple execute the matching
command, like Project.ShowAllFiles, or View.ViewCode for example. To
execute the commands use the DTE.ExecuteCommand() function.

Also, it's kind of difficult to figure out what a few of those buttons
actually execute. The EventWatcher sample addin is a good one to identify
the commands getting executed in the environment. It's available for
download at the following website:

 
http://www.microsoft.com/downloads/details.aspx?familyid=3ff9c915-30e5-430e-
95b3-621dccd25150&displaylang=en

Sincerely,
Ed Dore [MSFT]

This post is 'AS IS' with no warranties, and confers no rights.

It is not available for addins but I think that you can access it (to add
buttons, for example) using VSIP:

http://msdn.microsoft.com/vstudio/extend/