The back button still enable when LoadingDialog is showing

Describe the bug When the LoadingDialog is showing the back button press will go to last page.

To Reproduce Steps to reproduce the behavior: Here‘s two page ：

public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private async void Button_Clicked(object sender, EventArgs e)
        {
            View1 view1 = new View1();
           await Navigation.PushModalAsync(view1);
        }
    }

public partial class View1 : ContentPage
    {
        public View1()
        {
            InitializeComponent();
        }

        private async void Button_Clicked(object sender, EventArgs e)
        {
            var dialog = await MaterialDialog.Instance.LoadingDialogAsync(message: "获取数据中……");
            await Task.Delay(5000);
            dialog.Dispose();
        }
    }

When the loadingdialog is showing,I press back button on android,it back to MainPage, but the loadingdialog still showing,after 5s loadingdialog hide.

[contrix09]

Hi, did you override the OnBackPressed on Android like this:

public override void OnBackPressed()
{
    XF.Material.Droid.Material.HandleBackButton(base.OnBackPressed);
}

[vincywindy]

I override it,it works fine,thank you!