Make escape delay configurable via ncurses standard $ESCDELAY

Also reduce the default delay to 50ms. We should not set it to 0ms as it
breaks escape sequences on WSL. If 50ms is not enough, one can increase
the delay by setting $ESCDELAY to a larger value.

src/tui/ncurses.go

@@ -23,6 +23,7 @@ import "C"
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -103,8 +104,16 @@ func Init(theme *ColorTheme, black bool, mouse bool) {
 	C.raw() // stty dsusp undef
 	C.nonl()
 	C.keypad(C.stdscr, true)
-	C.set_escdelay(100)
-	C.timeout(100) // ESCDELAY 100ms + timeout 100ms
+
+	delay := 50
+	delayEnv := os.Getenv("ESCDELAY")
+	if len(delayEnv) > 0 {
+		num, err := strconv.Atoi(delayEnv)
+		if err == nil && num >= 0 {
+			delay = num
+		}
+	}
+	C.set_escdelay(C.int(delay))
 
 	_color = theme != nil
 	if _color {
@@ -293,8 +302,10 @@ func consume(expects ...rune) bool {
 }
 
 func escSequence() Event {
-	// nodelay is not thread-safe (e.g. <ESC><CTRL-P>)
-	// C.nodelay(C.stdscr, true)
+	C.nodelay(C.stdscr, true)
+	defer func() {
+		C.nodelay(C.stdscr, false)
+	}()
 	c := C.getch()
 	switch c {
 	case C.ERR: