GitLab

 src/xdisp.c (x_write_glyphs, draw_phys_cursor_glyph)
 (erase_phys_cursor, update_window_cursor, show_mouse_face)
 (cursor_in_mouse_face_p): If the cursor position is out of bounds,
 behave as if the cursor position were at the window margin.
 src/window.c (get_phys_cursor_glyph): If the window is hscrolled,
 and the cursor position is out of bounds, behave as if the cursor
 position were at the window margin.