Point tcell at stefanhaller's fork

This is temporary as long as https://github.com/gdamore/tcell/pull/599 is not
merged. Once that PR is merged, we can revert this.

vendor/github.com/gdamore/tcell/v2/tscreen.go

@@ -153,6 +153,8 @@ type tScreen struct {
 	enterUrl     string
 	exitUrl      string
 	setWinSize   string
+	enableFocus  string
+	disableFocus string
 	cursorStyles map[CursorStyle]string
 	cursorStyle  CursorStyle
 	saved        *term.State
@@ -161,6 +163,7 @@ type tScreen struct {
 	wg           sync.WaitGroup
 	mouseFlags   MouseFlags
 	pasteEnabled bool
+	focusEnabled bool
 
 	sync.Mutex
 }
@@ -366,6 +369,17 @@ func (t *tScreen) prepareExtendedOSC() {
 	} else if t.ti.Mouse != "" {
 		t.setWinSize = "\x1b[8;%p1%p2%d;%dt"
 	}
+
+	if t.ti.EnableFocusReporting != "" {
+		t.enableFocus = t.ti.EnableFocusReporting
+	} else if t.ti.Mouse != "" {
+		t.enableFocus = "\x1b[?1004h"
+	}
+	if t.ti.DisableFocusReporting != "" {
+		t.disableFocus = t.ti.DisableFocusReporting
+	} else if t.ti.Mouse != "" {
+		t.disableFocus = "\x1b[?1004l"
+	}
 }
 
 func (t *tScreen) prepareCursorStyles() {
@@ -1043,6 +1057,32 @@ func (t *tScreen) enablePasting(on bool) {
 	}
 }
 
+func (t *tScreen) EnableFocus() {
+	t.Lock()
+	t.focusEnabled = true
+	t.enableFocusReporting()
+	t.Unlock()
+}
+
+func (t *tScreen) DisableFocus() {
+	t.Lock()
+	t.focusEnabled = false
+	t.disableFocusReporting()
+	t.Unlock()
+}
+
+func (t *tScreen) enableFocusReporting() {
+	if t.enableFocus != "" {
+		t.TPuts(t.enableFocus)
+	}
+}
+
+func (t *tScreen) disableFocusReporting() {
+	if t.disableFocus != "" {
+		t.TPuts(t.disableFocus)
+	}
+}
+
 func (t *tScreen) Size() (int, int) {
 	t.Lock()
 	w, h := t.w, t.h
@@ -1380,6 +1420,35 @@ func (t *tScreen) parseSgrMouse(buf *bytes.Buffer, evs *[]Event) (bool, bool) {
 	return true, false
 }
 
+func (t *tScreen) parseFocus(buf *bytes.Buffer, evs *[]Event) (bool, bool) {
+	state := 0
+	b := buf.Bytes()
+	for i := range b {
+		switch state {
+		case 0:
+			if b[i] != '\x1b' {
+				return false, false
+			}
+			state = 1
+		case 1:
+			if b[i] != '[' {
+				return false, false
+			}
+			state = 2
+		case 2:
+			if b[i] != 'I' && b[i] != 'O' {
+				return false, false
+			}
+			*evs = append(*evs, NewEventFocus(b[i] == 'I'))
+			_, _ = buf.ReadByte()
+			_, _ = buf.ReadByte()
+			_, _ = buf.ReadByte()
+			return true, true
+		}
+	}
+	return true, false
+}
+
 // parseXtermMouse is like parseSgrMouse, but it parses a legacy
 // X11 mouse record.
 func (t *tScreen) parseXtermMouse(buf *bytes.Buffer, evs *[]Event) (bool, bool) {
@@ -1556,6 +1625,12 @@ func (t *tScreen) collectEventsFromInput(buf *bytes.Buffer, expire bool) []Event
 			partials++
 		}
 
+		if part, comp := t.parseFocus(buf, &res); comp {
+			continue
+		} else if part {
+			partials++
+		}
+
 		// Only parse mouse records if this term claims to have
 		// mouse support
 
@@ -1804,6 +1879,9 @@ func (t *tScreen) engage() error {
 	t.stopQ = stopQ
 	t.enableMouse(t.mouseFlags)
 	t.enablePasting(t.pasteEnabled)
+	if t.focusEnabled {
+		t.enableFocusReporting()
+	}
 
 	ti := t.ti
 	t.TPuts(ti.EnterCA)
@@ -1853,6 +1931,7 @@ func (t *tScreen) disengage() {
 	t.TPuts(ti.ExitKeypad)
 	t.enableMouse(0)
 	t.enablePasting(false)
+	t.disableFocusReporting()
 
 	_ = t.tty.Stop()
 }