keyboard supports !a to indicate release a

src/device/input/buffered.go

@@ -44,6 +44,8 @@ func (b *Buffered) listen() {
 		for i := range buttons {
 			if buttons[i].Down {
 				b.keys[buttons[i].Char] = time.Now().UnixNano()
+			} else {
+				b.keys[buttons[i].Char] = 0
 			}
 		}
 		b.lock.Unlock()

src/device/input/keyboard.go

@@ -50,10 +50,14 @@ func (kb Keyboard) Read() []Button {
 		panic(err)
 	}
 
+	down := true
 	result := make([]Button, 0, n)
 	for i := 0; i < n; i++ {
-		if b[i] != '\n' {
+		if b[i] == '!' {
-			result = append(result, Button{Char: b[i], Down: true})
+			down = false
+		} else if b[i] != '\n' {
+			result = append(result, Button{Char: b[i], Down: down})
+			down = true
 		}
 	}
 	return result

todo.yaml

@@ -0,0 +1,4 @@
+todo:
+- sticky keyboard input mode for enable/disable explicitly
+scheduled: []
+done: []