Available in LIB version 2017.1.213 , it will be also available in the R1 2017 SP1 Release.

Currently the new item's properties are validated before editing their values, which is not intuitive, especially for Required, MinLength etc. The correct behavior would suggest that validation should be applied only to "confirmed" property values.

To work this around you can set the EnableColumnGroupsVirtualization to False.

Alternatively you can change the FrozenColumnCount before adding the columns, and reset it once the process is done. For example:

gridTriffDetails.FrozenColumnCount = 0;
 
gridTriffDetails.Columns.Add(newColumn);
gridTriffDetails.Columns.Add(newColumn1);
gridTriffDetails.Columns.Add(newColumn2);
 
gridTriffDetails.FrozenColumnCount = 1;

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

Workaround: reused the cell element like this:
CreateCellElement(Telerik.Windows.Controls.GridView.GridViewCell cell, object dataItem)
{
    var button = cell.Content as Button;
    . . .
 
    return button;
}

When tabbing in grouped RadGridView placed in Grid with another visual element inside it, GroupRenderMode is set to Flat  and second group is not in ViewPort, selected row changed its state to Unfocused.

Currently, within the LoadItems() method the items are being iterated directly, thus a second query to the database is triggered.  A separate list for this operation should be created.

The issue is reproduced only with GroupRenderMode="Flat".

The problem should be resolved with lib version 2015.3.1130.