When a line is exactly as wide as the window, Emacs displays the cursor in the right fringe instead of using two lines. Different bitmaps are used to represent the cursor in the fringe depending on the current buffer’s cursor type.
user option overflow-newline-into-fringe
If this is non-
nil, lines exactly as wide as the window (not counting the final newline character) are not continued. Instead, when point is at the end of the line, the cursor appears in the right fringe.
This variable specifies the mapping from logical cursor type to the actual fringe bitmaps displayed in the right fringe. The value is an alist where each element has the form
(cursor-type . bitmap), which means to use the fringe bitmap
bitmap to display cursors of type
cursor-type should be one of
hollow-small. The first four have the same meanings as in the
cursor-type frame parameter (see Cursor Parameters). The
hollow-small type is used instead of
hollow when the normal
hollow-rectangle bitmap is too tall to fit on a specific display line.
bitmap should be a symbol specifying the fringe bitmap to be displayed for that logical cursor type. See Fringe Bitmaps.
fringe-cursor-alist has a buffer-local value, and there is no bitmap defined for a cursor type, the corresponding value from the default value of
fringes-indicator-alist is used.