[Bug] Scroll Bars appear on controls inside a CollectionView

[johnallan78]

Description

When I open a Time Picker inside a Collection View on Android, there are vertical scroll bars that appear in the dialog. I'm using a Holo theme and have attached a small repo to reproduce this. It's not a breaking change and has no effect on functionality, but they are a bit ugly and distracting. They don't appear if you are using ListView. For the purposes of this reproduction I have used a Time Picker control, but I have seen these scroll bars appear in Editor controls too.

Steps to Reproduce

1. Click on any Time Picker and you should see the scroll bars briefly appear.

Expected Behavior

No scroll bars to appear, as was the case when using ListView

Actual Behavior

Basic Information

• Version with issue:

• Last known good version:

• IDE: VS 2019 16.3.6/ 8.3.7(mac)

• Platform Target Frameworks:

  • Android:

• Android Support Library Version:

• Nuget Packages: Xamarin Forms 4.3.0

• Affected Devices: Google Pixel 4

Screenshots

Reproduction Link

https://github.com/johnallan78/CollectionViewTest

[johnallan78]

Just to clarify, this doesn't happen, or at least I can't reproduce the bug, when the control is not in a CollectionView

[jfversluis]

Confirmed this behavior. When you put a TimePicker outside the CollectionView you won't see the scrollbars flash while they do when opened from inside the CollectionView. Also happens with other scrollable controls.

[SoaringChris]

Also experiencing random scroll bars appearing in on labels within a grid as well as SegmentedControls created with Forms9Patch when placed in collection views. This was not an issue in older versions of Xamarin

[iamlawrencev]

Can confirm this bug. My case is that I have in controls in the Header of my CollectionView. It then displays a small scrollbar on the upper-right of the view similar to the screenshot above.

[moustafashaban]

this one is really annoying, I had to add Control.VerticalScrollBarEnabled = false; in the LabelRenderer to solve it, but I still see it in other places, especially with some controls inside a scroll viewer

[JKennedy24]

heres a workaround renderer for anyone who wants a quick workaround:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using MyApp.Droid.CustomRenderers.Controls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using Xamarin.Forms.Platform.Android.FastRenderers;

//workaround for this issue: https://github.com/xamarin/Xamarin.Forms/issues/8626
//also think there may be an issue on labels in general

[assembly: ExportRenderer(typeof(Label), typeof(MyAppLabelRenderer ))]
namespace MyApp.Droid.CustomRenderers.Controls
{
    class MyAppLabelRenderer : Xamarin.Forms.Platform.Android.FastRenderers.LabelRenderer
    {
        public MyAppLabelRenderer (Context context) : base(context)
        {

        }

        protected override void OnElementChanged(ElementChangedEventArgs<Label> e)
        {
            base.OnElementChanged(e);

            if (Control == null || e.NewElement == null)
            {
                return;
            }
            Control.VerticalScrollBarEnabled = false;
        }
    }
}

[aktxyz]

whew ... thought I was seeing things with these random scroll bars !! looks like will be fixed soon

[Edgaras91]

I am getting this issue with ScrollViews too! Buttons and checkboxes inside the scroll view "gain" a scroll bar, which is only visible on page load time (same time as scroll bar for scroll view appears). Controls are not actually scrollable. Everything scrolls in the scroll view as intended.