vis: add :set escdelay nn option

Make the delay used to distinguish between an <Escape> key and
other terminal escape sequences such as for the Meta key run
time configurable. The value is given in miliseconds and defaults
to 50ms.

Notice that terminal multiplexers like dvtm or tmux might also
induce some delay which has to be configured independently.

README.md

@@ -412,6 +412,11 @@ Operators can be forced to work line wise by specifying `V`.
 
        set shell to use for external commands (e.g. <, >, |)
 
+     escdelay   number          default 50 (50ms)
+
+       miliseconds to wait to distinguish between an <Escape> key and other
+       terminal escape sequences
+
      tabwidth   [1-8]           default 8
 
        set display width of a tab and number of spaces to use if

sam.c

@@ -281,6 +281,7 @@ typedef struct {
 
 enum {
 	OPTION_SHELL,
+	OPTION_ESCDELAY,
 	OPTION_AUTOINDENT,
 	OPTION_EXPANDTAB,
 	OPTION_TABWIDTH,
@@ -302,6 +303,11 @@ static const OptionDef options[] = {
 		OPTION_TYPE_STRING, OPTION_FLAG_NONE,
 		"Shell to use for external commands (default: $SHELL, /etc/passwd, /bin/sh)",
 	},
+	[OPTION_ESCDELAY] = {
+		{ "escdelay" },
+		OPTION_TYPE_NUMBER, OPTION_FLAG_NONE,
+		"Miliseconds to wait to distinguish <Escape> from terminal escape sequences",
+	},
 	[OPTION_AUTOINDENT] = {
 		{ "autoindent", "ai" },
 		OPTION_TYPE_BOOL, OPTION_FLAG_NONE,

vis-cmds.c

@@ -140,6 +140,12 @@ static bool cmd_set(Vis *vis, Win *win, Command *cmd, const char *argv[], Cursor
 		vis->shell = shell;
 		break;
 	}
+	case OPTION_ESCDELAY:
+	{
+		TermKey *termkey = vis->ui->termkey_get(vis->ui);
+		termkey_set_waittime(termkey, arg.i);
+		break;
+	}
 	case OPTION_EXPANDTAB:
 		vis->expandtab = arg.b;
 		break;