private async void Button_Clicked(object sender, EventArgs e)
{
var senderB = sender as Button;
var parent = senderB.Parent as StackLayout;
var idLabel = parent.Children[3] as Label;
int id = int.Parse(idLabel.Text);
Mark toDelte = await db.GetById <Mark>(id);
await db.DeleteMark(toDelte);
// update the subAves list on main page
var tabPage = this.Parent.Parent as TabbedPage;
var navPage = tabPage.Children[0] as NavigationPage;
var mainPage = navPage.CurrentPage as MainPage;
await mainPage.FillSubAves();
}
