This command captures the current image as a snapshot. To take a snapshot, use File/Take Snapshot or Ctrl+T. The command freezes the current frame, and displays a file dialog, allowing you to specify the output file's name and location.
Note that in Veejay mode, the file dialog is not displayed; in this case the snapshot is created in the default output folder, and its name is generated automatically. If the Use default folder option is set to "Always", taking a snapshot never displays a file dialog.