New config option for shifted arrow key handling.

This commit introduces a new config option for how to handle shifted
arrow keys.

In the default mode (SHARROW_APPLICATION), we do what we've always
done: Ctrl flips the arrow keys between sending their most usual
escape sequences (ESC [ A ... ESC [ D) and sending the 'application
cursor keys' sequences (ESC O A ... ESC O D). Whichever of those modes
is currently configured, Ctrl+arrow sends the other one.

In the new mode (SHARROW_BITMAP), application cursor key mode is
unaffected by any shift keys, but the default sequences acquire two
numeric arguments. The first argument is 1 (reflecting the fact that a
shifted arrow key still notionally moves just 1 character cell); the
second is the bitmap (1 for Shift) + (2 for Alt) + (4 for Ctrl),
offset by 1. (Except that if _none_ of those modifiers is pressed,
both numeric arguments are simply omitted.)

The new bitmap mode is what current xterm generates, and also what
Windows ConPTY seems to expect. If you start an ordinary Command
Prompt and launch into WSL, those are the sequences it will generate
for shifted arrow keys; conversely, if you run a Command Prompt within
a ConPTY, then these sequences for Ctrl+arrow will have the effect you
expect in cmd.exe command-line editing (going backward or forward a
word). For that reason, I enable this mode unconditionally when
launching Windows pterm.

1 files changed, 6 insertions, 0 deletions

diff --git a/config.c b/config.c
index 4c5da469..dd39862d 100644
--- a/config.c
+++ b/config.c
@@ -2016,6 +2016,12 @@ void setup_config_box(struct controlbox *b, bool midsession,
                       I(CONF_funky_type),
                       "ESC[n~", I(0), "Linux", I(1), "Xterm R6", I(2),
                       "VT400", I(3), "VT100+", I(4), "SCO", I(5), NULL);
+    ctrl_radiobuttons(s, "Shift/Ctrl/Alt with the arrow keys", 'w', 2,
+                      HELPCTX(keyboard_sharrow),
+                      conf_radiobutton_handler,
+                      I(CONF_sharrow_type),
+                      "Ctrl toggles app mode", I(SHARROW_APPLICATION),
+                      "xterm-style bitmap", I(SHARROW_BITMAP), NULL);
 
     s = ctrl_getset(b, "Terminal/Keyboard", "appkeypad",
                     "Application keypad settings:");