maintain scrollback buffer in left/right margin mode with default mar…

…gins (#916);

do not put cleared lines into scrollback buffer

src/term.c

@@ -1159,7 +1159,7 @@ term_do_scroll(int topline, int botline, int lines, bool sb)
     win_update(true);
   }
 
-  if (term.lrmargmode) {
+  if (term.lrmargmode && term.marg_left && term.marg_right != term.cols - 1) {
     scroll_rect(topline, botline, lines);
     return;
   }
@@ -1313,6 +1313,8 @@ term_erase(bool selective, bool line_only, bool from_begin, bool to_end)
   if (!from_begin || !to_end)
     term_check_boundary(curs->x, curs->y);
 
+#ifdef scrollback_erase_lines
+#warning this behaviour is not compatible with xterm
  /* Lines scrolled away shouldn't be brought back on if the terminal resizes. */
   bool erasing_lines_from_top =
     start.y == 0 && start.x == 0 && end.x == 0 && !line_only && !selective;
@@ -1335,7 +1337,9 @@ term_erase(bool selective, bool line_only, bool from_begin, bool to_end)
     if (!term.on_alt_screen)
       term.tempsblines = 0;
   }
-  else {
+  else
+#endif
+  {
     termline *line = term.lines[start.y];
     while (poslt(start, end)) {
       int cols = min(line->cols, line->size);

wiki/Changelog.md

@@ -1,4 +1,6 @@
 Terminal features
+  * Maintain scrollback buffer in left/right margin mode with default margins (#916).
+  * Do not put cleared lines into scrollback buffer.
   * Fixed display of subsequent identical emojis (since 3.0.1).
   * Mouse buttons 4 and 5 send the same escape sequences as xterm.
   * DECAUPSS to assign user-preferred supplemental sets to DECSUPP.