This behavior is reproducible when the SelectionUnit property of the RadGridView is set to "FullRow".
SelectedCells collection is not of the selected row updated when new columns are added runtime. For example, you have selected the first row which has 3 cells. Then you add 2 new columns. Now the row has 5 cells but the selected cells collection still have 3.

A possible workaround which can be used is to reset the SelectedItem property of the RadGridView.

var selectedItem = testGrid.SelectedItem;
testGrid.SelectedItem = null;
this.testGrid.Columns.Add(new GridViewDataColumn() { Header = "Value3", DataMemberBinding = new Binding("Value3"), Width = 100 });
this.testGrid.Columns.Add(CreateColumn("Value4", "Value4"));
testGrid.SelectedItem = selectedItem;

This behavior is observed when Office2013 theme is applied. 

Characters are lost when pressing multiple keyboard keys in quick succession.

To reproduce this:

1. Set the ShowToolTipOnTrimmedText property of RadGridView to True.
2. Hover a cell with trimmed text.
3. Before the tooltip shows, move the mouse quickly, outside of the RadGridView control.
4. Regardless of the fact that the mouse cursor is outside of the RadGridView control, the tooltip showing is not canceled and it shows after a second.

To resolve this, set the ShowToolTipOnTrimmedText of the gridview columns instead of the RadGridView control.

Expose a collection which holds the region of the currently selected cells.

for radgridview,if CanUserFreezeColumns="True" ,
when adjust the FreezeColumnsResizer to the right,and then resize the left colum'width,
if exceed the visual area,these exceed area's column will disappear!
for example,the data virtualization sample for the radgridview,if set the FreezeColumnsResizer
to the 'Unit_Price' column behind,then adjust the 'Product_ID' column width to exceed the visual area,
at last by scroll,you can't find the exceed visual area columns

Expose a SearchText property so that search as you type can be achieved through a custom TextBox instead of the GridViewSearchPanel.

Change the Default Selected Filter Operator:
https://docs.telerik.com/devtools/wpf/controls/radgridview/filtering/how-to/howto-change-the-default-selected-filter-operator

This doesn't work for boolean columns, if the property "ShouldGenerateFieldFilterEditors" of the column is set to "True". 

Please see the attached example.

*** The fix for this issue will be available with the next LIB (version 2018.3.1217) expected on Monday, December 17.

radGridView has a feature to provides a suggest and append feature.  Currently, there is the ability for the end user to inadvertently close this window.  Please provide the opportunity via a property to disable the ability to close the search window.  (currently, I am hooking the SearchPanelVisibilityChanged event, and forcing showSearchPanel = true at all times.

Scheduled for: 
The exposed property (SearchPanelCloseButtonVisibility) will be available with LIB (version 2018.3.1210) published on Monday, 10-th December, 2018. 

The fix for this issue will be available with the next LIB (version 2018.3.1203) expected on Monday, December 3.

Using such negative margin leads to some parts of the template to be actually outside of the control boundaries.

The fix for this issue will be available with the next LIB (version 2018.3.1203) expected on Monday, December 3.

The fix for this issue is available with LIB (version 2018.3.1126) published on Monday, November 26.

A workaround for the issue is to apply a 1px top Margin.

The fix for this issue is available with LIB (version 2018.3.1126) published on Monday, 26th November, 2018.

The fix for this issue will be available with the next LIB (version 2018.3.1126) expected on Monday, November 26.

Allow customizing the FieldFilterControl shown under the column header when the FilteringMode is set to FilterRow. Currently, you can customize this only via an implicit style or by looking into the gridview's visual tree in code. It would be useful if you can define a style per column.

A possible workaround is to show and hide the columns.

foreach (GridViewColumn col in TestGridView.Columns)
			{
				bool visibility = col.IsVisible;
				col.IsVisible = true;
				col.IsVisible = visibility;
			}