It is probably a de facto standard for user interfaces that windows are supposed to be scrolled by means of scrollbars attached to their sides. However, for various reasons the use of scrollbars has been minimized in gv.
Instead, in all windows with obscured data, scrolling may be performed by
pressing button1, moving the mouse, then releasing button1
directly in the window. This includes the displayed page, zoom popups, the table of contents and the file and directory lists displayed in the file selection popup.