The main window of a program doesn't have to be a resizable general purpose window.
Many small applications work better in a dialog box format.
The obvious advantage of such an approach is that you can use a resource editor to arrange all your controls on the surface of the box. This is in fact how the UI of the Frequency Analyzer was implemented. Since this is a useful technique, I will describe it in some detail. First of all, we have to design the dialog box using the resource editor. We assign identifiers to all the controls and to the dialog itself.