Where is the problem?
|directory exporter | directory := FileSystem workingDirectory / 'pictures' . directory ensureCreateDirectory. exporter := DOScreenshotExporter new. exporter directory: directory. exporter writeWorldAs: 'world.png'.
with DOScreenshotExporter>>writeWorldAs: aFileName (directory / aFileName) ensureDelete. PNGReadWriter putForm: World imageForm onFileNamed: (directory / aFileName).
though this form might not work DOScreenshotExporter>>writeMorph: aMorph rectangle: aRectangle as: aFileName (directory / aFileName) ensureDelete. PNGReadWriter putForm: (aMorph imageFormForRectangle: aRectangle) onFileNamed: (directory / aFileName).