xC + frontends: merge M-! into M-a + reversed M-A

Both WeeChat and irssi merge these two by prioritising highlights
when you press M-a.

xA/xA.go

@@ -1420,7 +1420,7 @@ func (l *customLayout) Layout(objects []fyne.CanvasObject, size fyne.Size) {
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-// rotatedBuffers returns buffer indexes starting with the current buffer.
+// rotatedBuffers returns buffer indexes starting after the current buffer.
 func rotatedBuffers() []int {
 	r, start := make([]int, len(buffers)), 0
 	for i := range buffers {
@@ -1458,6 +1458,29 @@ func actionBufferLast() {
 	}
 }
 
+func actionBufferActivity(backwards bool) {
+	r := rotatedBuffers()
+	if len(r) == 0 {
+		return
+	}
+	r = r[:len(r)-1]
+	if backwards {
+		slices.Reverse(r)
+	}
+	for _, i := range r {
+		if buffers[i].highlighted {
+			bufferActivate(buffers[i].bufferName)
+			return
+		}
+	}
+	for _, i := range r {
+		if buffers[i].newMessages != 0 {
+			bufferActivate(buffers[i].bufferName)
+			return
+		}
+	}
+}
+
 var shortcuts = map[desktop.CustomShortcut]func(){
 	{
 		KeyName:  fyne.KeyPageUp,
@@ -1487,28 +1510,17 @@ var shortcuts = map[desktop.CustomShortcut]func(){
 		KeyName:  fyne.KeyTab,
 		Modifier: fyne.KeyModifierAlt,
 	}: actionBufferLast,
-	{
-		// XXX: This makes an assumption on the keyboard layout (we want '!').
-		KeyName:  fyne.Key1,
-		Modifier: fyne.KeyModifierAlt | fyne.KeyModifierShift,
-	}: func() {
-		for _, i := range rotatedBuffers() {
-			if buffers[i].highlighted {
-				bufferActivate(buffers[i].bufferName)
-				break
-			}
-		}
-	},
 	{
 		KeyName:  fyne.KeyA,
 		Modifier: fyne.KeyModifierAlt,
 	}: func() {
-		for _, i := range rotatedBuffers() {
-			if buffers[i].newMessages != 0 {
-				bufferActivate(buffers[i].bufferName)
-				break
-			}
-		}
+		actionBufferActivity(false)
+	},
+	{
+		KeyName:  fyne.KeyA,
+		Modifier: fyne.KeyModifierAlt | fyne.KeyModifierShift,
+	}: func() {
+		actionBufferActivity(true)
 	},
 	{
 		KeyName:  fyne.KeyH,