Available in LIB version 2017.3.1204, it will be also available in the R1 2018 Release.

The reason for declining the item is that a possible fix for this behavior would practically interfere with the virtualization mechanism of the control. Shortly said, when the columns have their width initially set, RadGridView is aware of the column with the biggest size and performs its calculations based on it. When their size is changed on loading, the control cannot be aware of the size of a column that is not present in the viewport thus, the reported issue is observed. In order this behavior to be modified so, the engine needs to measure an element that is not yet loaded. We cannot commit ourselves to implementing this, as this would affect the virtualization of RadGridView. A possible workaround would be to avoid setting the Width of the columns initially in XAML.

When applying VQCV with custom IEnumerable as a source to the ItemsSource of the grid and filters grid through filtering control, ExportToXlsx exports wrong items.

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

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

The expanded state of the hierarchical item is not preserved when searching thought search panel for something that is not found and clearing search text.

Available in LIB version 2017.3.1113, it will be also available in the R1 2018 Release.

When setting the VirtualItemCount on refreshing the data source, the scrollbar jumps to the top. If the VirtualItemCount is initially set, the behavior is not reproduced. The workaround is to use the scrolling mechanism of the control and scroll back to the desired item.

Currently, the default value of the property is true, so the presented of items in the hierarchy collection is not taken into account. This results in having visible hierarchy buttons for rows that do not have hierarchical subitems.

Currently, you can use only the predefined one - IsEqual, IsNotEqual, etc. Add an option to create operators that execute custom filtering action. Also, add support for modifying the default operators.

Add option in GridViewDocumentExportOptions to include / exclude GroupHeaderRowAggregates.

This will allow users to hide/show group header row aggregates in the exported documents.

Option will be globbally applied - to all group header rows in the RadGridView.
===
From 2017 R3 SP GridViewDocumentExportOptions  adds ShowGroupHeaderRowAggregates bool property.

It can be used like so:

  GridViewDocumentExportOptions options = new GridViewDocumentExportOptions()
            {
                ShowGroupHeaderRowAggregates = true
            };
this.gridView.ExportToWorkbook(options);

Currently, the following workaround can be applied:

private void RadGridView_Loaded(object sender, RoutedEventArgs e)
{
	var gridView = sender as RadGridView;
	foreach (var column in gridView.Columns)
	{
		if (!column.IsResizable)
		{
			Dispatcher.BeginInvoke((Action) (() =>
			{
				var radGridView = column.Parent;
				foreach (var header in radGridView.ChildrenOfType<GridViewHeaderCell>())
				{
					if (header.Column.DisplayIndex == column.DisplayIndex)
					{
						var leftGripper = header.ChildrenOfType<Thumb>().Where(x => x.Name == "PART_LeftHeaderGripper").First();
						{
							leftGripper.Visibility = Visibility.Collapsed;
						}
					}
					else if (header.Column.DisplayIndex == (column.DisplayIndex - 1))
					{
						var rightGripper = header.ChildrenOfType<Thumb>().Where(x => x.Name == "PART_RightHeaderGripper").First();
						{
							rightGripper.Visibility = Visibility.Collapsed;
						}
					}
				}
			}), DispatcherPriority.Render);
		}
	}
}

Edit:
We are declining this bug as originally the export options were not meant to respect group properties but only some global GridView properties.
However we will add such option in GridViewDocumentExportOptions class.
You can follow this feature request => 
https://feedback.telerik.com/Project/143/Feedback/Details/229211-gridview-add-option-in-gridviewdocumentexportoptions-to-include-exclude-grouph

Same as the one available in Excel. Please check the attached screenshot.

This is reproducible in a hierarchical scenario. The nested gridview loses its selection when its parent row is scrolled out of the viewport.

Currently VQCV caches all the items once they are loaded. In this way the data virtaulization functions only through the first bottom-most item scrolling. The idea behind this item is to make this behavior optional by introducing an alternative mode.

I have a RadGridView and bind its ItemsSource and its SelectedItem to properties of the ViewModel (DataContext). When the ViewModel is created, the property bound to ItemsSource is filled and the property bound to SelectedItem is set to one of the items in the collection.

However, when the GridView is displayed, the property is first set to null and then set to the first item in the collection. I assume that the binding of the SelectedItem is evaluated before the binding of the ItemsSource, so the grid is empty and the desired item can't be selected. Is there any way to influence the order, in which the binding are evaluated? Or is there any other way to avoid that the SelectedItem is changed?

A similar issue is described here: http://www.telerik.com/forums/selecteditem-binding-issue
Unfortunately, I couldn't to find the support ticket mentioned in this thread.