How to block generic drag&drop handler for images?

I am learning blazor and I wanted to test moving images programmatically -- I added my handler to mousedown and mousemove and I can see I am moving images. Until the amount of movement triggers generic drag&drop mechanism and my methods are basically blocked.

So I would like to block this generic drag&drop handler and handle moving images on my own. How to do it?

Just for the record, the code:

<img src=@tile style="position:fixed; left:@(tileX)px; top:@( tileY)px;  border:none;" 
  @onmousemove="MouseMoved" @onmousedown="MouseDown"/>


@code {
  private string tile = "/images/eye.jpg";
  private int tileX = 0;
  private int tileY = 10;
  private double mouseX = 0;
  private double mouseY = 0;

private void MouseMoved(MouseEventArgs args)
{
    if (args.Buttons==1)
    {
        tileX += (int)Math.Round(args.ScreenX - mouseX);
        tileY += (int)Math.Round(args.ScreenY - mouseY);
        mouseX = args.ScreenX;
        mouseY = args.ScreenY;
    }
}

private void MouseDown(MouseEventArgs args)
{
    if (args.Buttons == 1)
    {
        mouseX = args.ScreenX;
        mouseY = args.ScreenY;
    }
}