In C/SIDE you can either acquire new controls by buying them or developing them yourself.
Buy or Develop Controls
You can buy a third-party control and use it in C/SIDE, as long as the control fits within the restrictions imposed. In short, these restrictions are:
Only non-visual controls are supported.
Events are not supported.
To develop a control yourself, you need a suitable tool. Currently, the recommended tools are:
Microsoft Visual C++ 4.0, or later
Microsoft Visual Basic 5.0
There are other tools available, but the tools mentioned here have been tested with C/SIDE. Furthermore, they both have highly efficient wizards that make creating controls much easier.
The controls that are created with the wizards are larger than controls that you can create directly. They also require additional runtime libraries, for example, controls created with the wizards in Microsoft Visual C++ require the Microsoft Foundation Classes runtime library. This is an important consideration when creating controls that are meant to be loaded over the Internet. This is probably less important for controls distributed as extensions to C/SIDE.