Add ctrl+z as undo (if allowed by terminal, hopefully)

README.md

@@ -67,7 +67,7 @@ Run the interactive terminal UI, useful for debugging or observing behavior. Pas
 - `A`-`Z`, `a`-`z`, `0`-`9`, and other printable characters: write character to grid at cursor
 - Spacebar: play or pause
 - `ctrl+f`: step the simulation one tick forward
-- `ctrl+u`: undo
+- `ctrl+z` or `ctrl+u`: undo
 - return or enter: change into or out of overwrite/append mode
 - `/`: change into or out of key-trigger mode (for the `!` operator)
 - `[` and `]`: Adjust cosmetic grid rulers horizontally

tui_main.c

@@ -1093,9 +1093,11 @@ int main(int argc, char** argv) {
   // ncurses state consistent, at the cost of less responsive terminal
   // interrupt. (This will rarely happen.)
   intrflush(stdscr, FALSE);
-  // Receive keyboard input immediately, and receive shift, control, etc. as
+  // Receive keyboard input immediately without line buffering, and receive
-  // separate events, instead of combined with individual characters.
+  // ctrl+z, ctrl+c etc. as input instead of having a signal generated. We need
-  // raw();
+  // to do this even with wtimeout() if we don't want ctrl+z etc. to interrupt
+  // the program.
+  raw();
   // Don't echo keyboard input
   noecho();
   // Also receive arrow keys, etc.
@@ -1212,6 +1214,7 @@ int main(int argc, char** argv) {
     case KEY_RIGHT:
       app_move_cursor_relative(&app_state, 0, 1);
       break;
+    case AND_CTRL('z'):
     case AND_CTRL('u'):
       app_input_cmd(&app_state, App_input_cmd_undo);
       break;