An implicit style could be added:

<Style TargetType="telerik:FilteringControl" BasedOn="{StaticResource FilteringControlStyle}">
   <Setter Property="Background" Value="{telerik:FluentResource ResourceKey=AlternativeBrush}" />
</Style>

A TargetName = "FilterIcon" should be added to the foreground setter in the trigger in the control template of the FilteringDropDown.

The performance of the RadGridView scrolling diminishes significantly when the grid has thousands of rows and alternating row styles are used.  This causes scrolling to be virtually unusable.  I note this is a known limitation of the RadGridView from information from https://docs.telerik.com/devtools/wpf/controls/radgridview/troubleshooting/performance 

We have had to remove the alternating row styles from our current product while porting to the RadGridView.  I am requesting if this issue is going to be fixed in the future anytime soon.

To reproduce the problem, there need to be defined a huge amount of columns(400-500). The workaround is to call the Clear method of the Columns collection of RadGridView

Available in LIB version 2018.1.122, it will be also available in the R1 2018 SP Release.

The fix is available in the R1 2018 Release.

Currently, RadGridView's data engine relies on TypeDescriptor.GetProperties, when resolving the set of properties accessible through a certain type. Apparently, this API hides the properteis from the interface, as they are not accessible throught the concrete type.

The unconfirmed inputs of filter row editors are being destroyed together with the editor itself in column-visualized GridViews. There's an easy solution for it (store what was in there and restore upon recreation) and we're waiting for an official fix for this "expected behaviour" since three+ years.

Available in LIB version 2018.1.205, it will be also available in the R1 2018 SP2 Release.

As of R1 2018 the GetCellContent method is no longer used for exporting a custom column content. Instead, the GetExportCellContent one of GridViewBoundColumnBase needs to be overriden.

Similar to the one in RadPivotGrid:
https://docs.telerik.com/devtools/wpf/controls/radpivotgrid/features/localdatasourceprovider/serialization

And here is an online demo:
https://demos.telerik.com/silverlight/#PivotGrid/Serialization

I have a RadGridView and bind its ItemsSource and its SelectedItem to properties of the ViewModel (DataContext). I use a ViewModel for the grid items with overridden Equals and GetHashCode. When the ViewModel is created, the property bound to ItemsSource is filled and the property bound to SelectedItem is set to an item that is equal to one of the items in the collection (but not reference equal).

Problem:
When the GridView is displayed, no item is selected.

Note: I already reported this issue before: https://feedback.telerik.com/Project/143/Feedback/Details/227302-binding-itemssource-and-selecteditem-of-gridview-changes-selecteditem
but now I have managed to modify the sample project so that the problem can be reproduced. The difference to the original sample project is that Equals and GetHashCode of the Club ViewModel are overridden and the selected item is not reference equal to the item in the collection.

When RadGridView is bound to a ListCollectionView and the SortDescriptions are set, columns with a SortMemberPath different from the DataMemberBinding don't display the sort indicator in the column header.

In the attached example the "Status" and "ETA" columns are sorted. "Status" header does not display the indicator due to the SortMemberPath being different from the DataMemberBinding.

Available in LIB version 2017.3.1127, it will be also available in the R1 2018 Release.