There is no way to directly copy pictures in Viewer or Moscow to another application using pull down menu options.
The recommended solution to this problem is to capture an image of the screen and open the file created in the other application you wish to use.
To capture an image of the screen press the ALT key (bottom left of keyboard) and the PRINT SCREEN key (top right of the keyboard) at the same time and this copies an image of the screen into the clipboard. Start up your other application and paste the image into the document.
To capture a copy of a portion of the screen to a file press APPLE-SHIFT-4. After pressing and releasing this combination drag across that portion of the screen you want to take a picture of. A file called 'picture #' where # is a unique number will be created on the top level of the startup disk. This file can then be opened in any graphics application or SimpleText. If you wish to copy a portion of the screen to the clipboard press APPLE-SHIFT-4 and while dragging hold down the CONTROL key. This can then be pasted into you other application.
To capture a portion of the screen start the application SNAPSHOT (either from a UNIX window or from an icon of the desktop). A button called SNAPSHOT will appear on the desktop. With the right mouse button a popup menu can be triggered on that button to change the file name to which the snapshot will be written and also to trigger the snapshot. To select the position of the screen to be captured drag the box (it will appear automatically once you press the left mouse button) with the left mouse button from the SNAPSHOT button across the screen. Once the rectangle is correctly positioned trigger a snapshot. This will be saved in your upper level directory in a file called 'snap.rgb' if you didn't change the filename (it will overwrite any existing file). This file can then be opened in SHOWCASE, IMGVIEW or any other drawing or photo editing package that can read an SGI RGB format file.