AnsiTerm mode is great for terminal emulation. It behaves like a full-featured terminal in term-char mode, and like a regular Emacs buffer in term-line mode. But it does have a few complications and annoyances. Interaction with Cua-mode and Transient-mark-modeAnsiTerm mode disables Cua-mode because, as stated in the term.el file, “Cua-mode’s keybindings interfere with the term keybindings”. If you