RadComboBox Flicker between two items when scrolling on Windows 11 Theme

[Julio]

Our QA Team identified a bug and we were able to replicated on Telerik Control Example Application. we have being trying to fixit but so far we have not found a solution to the problem.

Replication Steps(please see video and gif attached):

1. Open a RadComboBox
   1. RadComboBox with many items (enough items to trigger the scrollbar or set a max width to trigger it)
   2. RadComboBox using Windows 11 Theme
2. Place the mouse between two items
3. Scroll without moving the mouse

Is there any way of fixing this from our end?

Kind regard

Julio

[Stenly]

Hello Julio,

I was able to reproduce this behavior on my end as well. As a result of this, I have logged a new bug report in our feedback portal, which can be found at the following link:

ComboBox: Items in the drop-down menu flicker when Windows 11 theme is applied (telerik.com)

In the meantime, to work this around, a new Style with TargetType="RadComboBoxItem" could be created for the ItemContainerStyle property of RadComboBox. Then, set the BorderBrush and ThemeHelper.MouseOverBrushproperties to "#F9F9F9".

The following code snippet shows this suggestion's implementation:

xmlns:helpers="clr-namespace:Telerik.Windows.Controls.Theming.Helpers;assembly=Telerik.Windows.Controls"

<telerik:RadComboBox.ItemContainerStyle>
    <Style TargetType="telerik:RadComboBoxItem">
        <Setter Property="helpers:ThemeHelper.MouseOverBrush" Value="#F9F9F9" />
        <Setter Property="BorderBrush" Value="#F9F9F9"/>
    </Style>
</telerik:RadComboBox.ItemContainerStyle>

In addition, I have updated your Telerik points as a token of gratitude for bringing this to our attention.

With this being said, could you give this suggestion a try?

Regards,
Stenly
Progress Telerik