Autodesk Revit API application: NewOpenings

This is a sample that shows how to Create Opening in Revit by RevitAPI

To build the *.dll, edit project properties and make sure additional reference component
include the Revit.dll in Revit Building 10 installation directory. 
Then, paste the contents of Revit.ini into Revit.ini. 
Launch Revit, note the Tools -> External Tools -> NewOpenings Commands menu.

The program is to display a form to show the profile of Floor (or Wall) on the preview, user can use draw Opening on the preview, and create.
1. Display the profile of Floor (or Wall)
2. Allow the user to draw opening on preview
3. click "Create" button to create Opening drawed on preview in Revit
