P.Brian.Mackey P.Brian.Mackey - 4 months ago 26
C# Question

How do you add an existing form to a new project?

I have never been able to successfully add a new

file as an existing file to a new project. I read on a blog that you add just the *.cs file and the dependencies come in. Well, I tried this and the file did dragin and associate the *.designer and *.resx files. But, the Form icon does not display. Instead, the file looks like a normal *.cs file image. And, when I double click the file I get the code behind instead of the form object.

Is it possible to add existing Forms without recreating them?


After some more research I discovered the source of the issue. It is correct that all one has to import is the *.cs file. The caveat lies in the project type. If working in a Class Library project, another step must be performed.

  1. Add a reference to System.Windows.Forms.dll and System.Drawing.
  2. Import the *.cs file


A. The files are only properly recognized after I performed these steps and then tried to open the file. Suddenly VS "wakes up" and fixes the files.
B. Order of the steps does not matter. If you already imported *.cs files, just fix the references.
C. If one is missing other references (E.G. DevExpress or other 3rd party Control imports), the *.cs files will not display properly until this has been resolved.