PTEditor is a Java based tool that displays a spherical panorama much the same way as PTViewer. It runs on any OS that has Java and a panotools library (pano12 or libpano12, depending on OS) installed - this currently precludes native OSX support. If you want to start PTEditor by double click make sure JAR files are linked to the Java Virtual Machine.
Amongst other functions PTEditor provides a very convenient way to extract partial rectilinear views from spherical panoramas and insert them again after having edited them. PTEditor loads equirectangular panorama files in JPEG, PNG, TIFF or BMP format.