What event do i use to trigger something like a mousedown in XAML (XamarinForms)

I want to be able to fire an event when the user is doing like a mousedown on a grid. (Like a visual feedback that the user is tapping the grid but not a click!)

I have this XAML code:

 <Grid.Triggers>
    <EventTrigger Event="MouseDown">
        <local:MouseOver/>
    </EventTrigger>
</Grid.Triggers>

And this in a c# class:

 public class MouseOver : TriggerAction<Entry>
{
    protected async override void Invoke(Entry entry)
    {
        //Some animation code here
    }
}

Well i am never able to get in the event, even though the class is implemented correctly! I also tried "IsMouseOver" and "MouseEnter" as Events but none of that seems to work. I hope someone here can help me... Thx for your help!