If you supply your own icons, as <application_name>.icns (Mac) or
<application_name>.ico (Windows) in the icons directory, these will be 
used when you build the applications.

Example, for ApplicationName "PraatDemoApp":
PraatDemoApp.icns
PraatDemoApp.ico

If you have "convert" installed, other image formats will be converted 
to .ico (Windows) icons. This works for .jpg, .png, .tiff.