fix: special case modified f3 key and cursor pos report

A modified F3 key press has the same sequence as cursor position report.
We need to handle that by reporting both messages and letting the
program determine which one to listen for. On most cases, programs don't
care about modified F3 key press since terminals tend to have different
sequences for it.

key_test.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"math/rand"
 	"reflect"
+	"regexp"
 	"runtime"
 	"sort"
 	"strings"
@@ -63,12 +64,23 @@ type seqTest struct {
 	msgs []Msg
 }
 
+var f3CurPosRegexp = regexp.MustCompile(`\x1b\[1;(\d+)R`)
+
 // buildBaseSeqTests returns sequence tests that are valid for the
 // detectSequence() function.
 func buildBaseSeqTests() []seqTest {
 	td := []seqTest{}
 	for seq, key := range sequences {
-		td = append(td, seqTest{[]byte(seq), []Msg{KeyPressMsg(key)}})
+		k := KeyPressMsg(key)
+		st := seqTest{seq: []byte(seq), msgs: []Msg{k}}
+
+		// XXX: This is a special case to handle F3 key sequence and cursor
+		// position report having the same sequence. See [parseCsi] for more
+		// information.
+		if f3CurPosRegexp.MatchString(seq) {
+			st.msgs = []Msg{k, CursorPositionMsg{Row: 1, Column: int(key.Mod) + 1}}
+		}
+		td = append(td, st)
 	}
 
 	// Additional special cases.
@@ -219,7 +231,12 @@ func TestParseSequence(t *testing.T) {
 			buf := tc.seq
 			for len(buf) > 0 {
 				width, msg := parseSequence(buf)
-				events = append(events, msg)
+				switch msg := msg.(type) {
+				case multiMsg:
+					events = append(events, msg...)
+				default:
+					events = append(events, msg)
+				}
 				buf = buf[width:]
 			}
 			if !reflect.DeepEqual(tc.msgs, events) {

parse.go

@@ -300,23 +300,26 @@ func parseCsi(b []byte) (int, Msg) {
 		return i, BlurMsg{}
 	case 'R':
 		// Cursor position report OR modified F3
-		if paramsLen == 0 {
-			return i, KeyPressMsg{Sym: KeyF3}
-		} else if paramsLen != 2 {
-			break
+		if paramsLen == 2 {
+			m := CursorPositionMsg{Row: csi.Param(0), Column: csi.Param(1)}
+			if csi.Param(0) == 1 && csi.Param(1)-1 <= int(ModMeta|ModShift|ModAlt|ModCtrl) {
+				// XXX: We cannot differentiate between cursor position report and
+				// CSI 1 ; <mod> R (which is modified F3) when the cursor is at the
+				// row 1. In this case, we report both messages.
+				//
+				// For a non ambiguous cursor position report, use
+				// [ansi.RequestExtendedCursorPosition] (DECXCPR) instead.
+				return i, multiMsg{KeyPressMsg{Sym: KeyF3, Mod: KeyMod(csi.Param(1) - 1)}, m}
+			}
+
+			return i, m
 		}
 
-		// XXX: We cannot differentiate between cursor position report and
-		// CSI 1 ; <mod> R (which is modified F3) when the cursor is at the
-		// row 1. In this case, we report a modified F3 event since it's more
-		// likely to be the case than the cursor being at the first row.
-		//
-		// For a non ambiguous cursor position report, use
-		// [ansi.RequestExtendedCursorPosition] (DECXCPR) instead.
-		if csi.Param(0) != 1 {
-			return i, CursorPositionMsg{Row: csi.Param(0), Column: csi.Param(1)}
+		if paramsLen != 0 {
+			return i, UnknownMsg(b[:i])
 		}
 
+		// Unmodified key F3 (CSI R)
 		fallthrough
 	case 'a', 'b', 'c', 'd', 'A', 'B', 'C', 'D', 'E', 'F', 'H', 'P', 'Q', 'S', 'Z':
 		var k KeyPressMsg