I can't use UserControls in winform c#.net

... June 5 edit ... based on research that indicates that Visual Studio Express does not have the "Windows Forms Control Library" template ...

Assuming you are using: Visual Studio Express 2013 for Windows Desktop, try this:

1. Open New Project, Select a Project Type of 'Class Library'

2. Manually add the references to System.Windows.Forms and System.Drawing and any other references your UserControl requires

3. Add a UserControl: design it, code it.

4. When you compile/save this Project it will create a .dll

To re-use the UserControl in a new WinForms Application Project:

1. Select a ToolBox Tab, context-select "Add New Item"

2. Choose Browse: navigate to the Project of type Class Library where you created the UserControl

3. find the compiled .dll for that Class Lbrary Project: select it: hopefully it will appear in the ToolBox


... end June 5 edit ...

Checklist:

0. the UserControl has a parameterless constructor ?

1. you created the UserControl with no indirect dependencies on other files, dll's, Controls, Forms, etc. ?

2. you created the UserControl as a Project of Type "Windows Forms Control Library" ?

3. you created a new WinForms project where you wanted to re-use the compiled UserControl where:

a. you context-clicked on the ToolBox in some existing Tab, selected 'Add New Item' and then browsed in the selector dialog Form to the UserControl dll ?

b. the UserControl now appears in the ToolBox ?

4. did you register/install the Assembly of the UserControl ? (if you expect the Control to persist in the ToolBox every time you open a new project) ... I suspect this is not relevant to you, but, if it is, see: [^]