TextViewImeActionBinding

    public class TextViewImeActionBinding : MvxAndroidTargetBinding
    {
        private bool subscribed;
        private ICommand _command;

        protected TextView TextView
        {
            get { return Target as TextView; }
        }

        public static void Register(IMvxTargetBindingFactoryRegistry registry)
        {
            registry.RegisterCustomBindingFactory<TextView>("ImeAction", view => new TextViewImeActionBinding(view));
        }

        public TextViewImeActionBinding(TextView view) : base(view)
        {
            if (view == null)
                Mvx.Trace(MvxTraceLevel.Error, "TextViewImeActionBinding : view is null");
        
            if (view != null)
            {
                TextView.EditorAction += ViewOnEditorAction;
                subscribed = true;
            }
        }

        private void ViewOnEditorAction(object sender, TextView.EditorActionEventArgs args)
        {
            FireValueChanged(args.ActionId);

            //args.ActionId
            args.Handled = true;
            if (_command == null)
                return;

            _command.Execute(((TextView)sender).Text);
        }

        public override Type TargetType
        {
            get { return typeof(ICommand); }
        }

        public override MvxBindingMode DefaultMode
        {
            get { return MvxBindingMode.OneWay; }
        }

        protected override void SetValueImpl(object target, object value)
        {
            _command = (ICommand)value;
        }

        protected override void Dispose(bool isDisposing)
        {
            if (isDisposing)
            {
                var view = TextView;
                if (view != null && subscribed)
                {
                    view.EditorAction -= ViewOnEditorAction;
                }
            }
            base.Dispose(isDisposing);
        }
    }

TextViewImeActionBinding usage

            <TextView
                local:MvxBind="Text PasswordConfirm; ImeAction RegisterCommand"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="Password"
                android:inputType="textPassword"
                android:imeOptions="actionSend" />

Oh ! It works !!

I checked value in the debugger, but was not able to find an ICommand in it. Should be caused by an "incorrect" binding mode.

But should'nt it be a OneWayToSource binding ? (from target view to source viewmodel ?)

And because the binding mode is set to OneWay, SubscribeToEvents is not called anymore. That's why you removed it :)

I update the gist, as i fixed other errors. You can put the code in vnext if you want.