The window class name registered by SftButton_RegisterApp and used when creating a button with CreateWindow / CreateWindowEx or in a dialog resource.
#define SFTBUTTON_CLASS "SftButtonControl30"
Use SFTBUTTON_CLASS in preference to the literal string "SftButtonControl30" so that a future class-name change would not require a source code sweep.
In dialog resources defined through Visual Studio's resource editor, enter SftButtonControl30 in the Class field of the custom control's properties.
See Also RegisterApp | Creating a Dialog Resource