Call method in existing Com Application from my .NET application

There is a scenario I'm interested in. User runs COM based application in a separate window, I want my C# application to manipulate that application through COM calls. I've found COM interface I'm interested in and VisualStudio has successfully generated wrapper (MyApp.interop). So I can write something like new Interop.MyApplication() but I do not want new Application I want to 开发者_如何学编程work with existing one.

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I've found the solution, code looks like

var app = Marshal.GetActiveObject("MapInfo.Application")
((MyApp)app).OpenFile(...)