When a toolbar button is selected, the application is notified through the LToolbar::ToolbarCallBack function. To receive notification of toolbar events, you must derive a class from LToolbar and override the LToolbar::ToolbarCallBack function. In addition, the use of the callback function must be enabled by calling LToolbar::EnableToolbarCallBack.
Direct Show .NET | C API | Filters
Media Foundation .NET | C API | Transforms