Sometimes you may want to use the Add > Existing Project context menu of the Solution Explorer to add an executable as a project to the solution. For example, to force the debugger type (2.0, 4.0, etc.) for an add-in of such executable as described in Procedure 3 at:
HOWTO: Debug an add-in for the VBA editor (32-bit or 64-bit) of Office with Visual Studio .NET.
It happens that you add the executable inside a solution folder, you can't show its properties page. If you add it inside the solution node, you can.