 <p>A very simple GUI application is possible sticking with C and Windows API only.</p> <p>In short, you have to register your own Window class (<code>RegisterClassEx</code>), then create the window (<code>CreateWindowEx</code>). Note that your window class main element is its (<code>WindowProc</code>) that receive the messages and that you have to implement to act as you want. After that, your C program should run the message pump (<code>PeekMessage</code> and <code>DispatchMessage</code>) for Windows to do its stuff and allow interacting with your window.</p> <p>See the MSDN documentation for these functions to get help and examples.</p>