NCSA Mosaic for Microsoft Windows User's Guide
The mouse is the main navigational tool used within the NCSA Mosaic window. Unless otherwise specified, NCSA Mosaic for Microsoft Windows mouse actions require pressing the left button: pressing the left button while the cursor points to a hyperlink will cause NCSA Mosaic to follow that hyperlink; pressing the left button while the cursor points to a button will activate that button; all menu selections are performed with the left mouse button.
Holding the Shift key and pressing the left mouse button while the cursor is pointing to a hyperlink will cause the file associated with that hyperlink to be saved to a local disk instead of being displayed as the document is brought across the network. The file transfer is performed in binary mode. This action is equivalent to setting Options ... Load to Disk for a single file.
When Display Inline Images on the Options menu is turned off, an icon is displayed to hold the place of each inline image. Clicking on one of these place-holding icons with the right mouse button will cause the corresponding inline image to be displayed. Note that if the icon is part of a hyperlink, pressing the left button will cause NCSA Mosaic to follow the hyperlink; pressing the right button will cause the image to be loaded and displayed without following the hyperlink.
Since many users have only a two-button mouse, the center button on a three-button mouse is not used in NCSA Mosaic for Microsoft Windows.