VS PlugIn = TextBuffer change event

Hi

When i register to TextBuffer change evens, the function will invoke for each change in the text editor.

When the user write cw+tab (snippet that make Consolw.WriteLine()), the event fired multiple times,My question is, how can i know if the event is fire because the user do some changes on the editor or VS make the change (like snippet, add usings etc.)

Sorry about my English :-)