So I wanted a context menu that allowed me to delete all of the selected rows, or clone just the row that was right-clicked on.  This is what I did to get the right-click selection to work as expected.  In my XAML:

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                    <!-- Define context menu -->
                    <ContextMenu x:Key="RecordContextMenu">
                        <MenuItem Header="Delete Selected Rows" Click="grdConnectionManagerEntries_ContextMenuItem_Delete_Click" />
                        <MenuItem Header="Clone Selected Row" Click="grdConnectionManagerEntries_ContextMenuItem_Clone_Click" />
                    </ContextMenu>
                    <Style TargetType="{x:Type igDP:DataRecordCellArea}">
                        <Setter Property="ContextMenu" Value="{DynamicResource RecordContextMenu}"></Setter>
                    </Style>
                    <!-- Make right-click select the clicked row -->
                    <Style TargetType="{x:Type igDP:DataRecordPresenter}">
                        <EventSetter Event="PreviewMouseRightButtonUp" Handler="grdConnectionManagerEntries_DataRowPresenterRightClicked" />
                    </Style>
                </igDP:XamDataGrid.Resources>

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And then in my code-behind I have this:

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        void grdConnectionManagerEntries_DataRowPresenterRightClicked(object sender, MouseButtonEventArgs e)
        {
            DataRecordPresenter drp = sender as DataRecordPresenter;
            if (drp != null && drp.Record != null)
            {
                // If we right-clicked on a row that was already selected, then maintain all of the currently selected rows,
                // otherwise clear any other selected rows so that just this one row gets selected.
                if (!drp.Record.IsSelected)
                    grdConnectionManagerEntries.SelectedItems.Records.Clear();

                // Select this row and set it as the active row as well.
                drp.Record.IsSelected = true;
                grdConnectionManagerEntries.ActiveRecord = drp.Record;
            }
        }

        private void grdConnectionManagerEntries_ContextMenuItem_Delete_Click(object sender, RoutedEventArgs e)
        {
            DataPresenterCommands.DeleteSelectedDataRecords.Execute(null, grdConnectionManagerEntries);
        }

        private void grdConnectionManagerEntries_ContextMenuItem_Clone_Click(object sender, RoutedEventArgs e)
        {
            CreateAndShowNewConnecitonEntryWindow((grdConnectionManagerEntries.ActiveDataItem as DataRowView).Row as Connection);
        }

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I should point out though that I'm only dealing with Records in my XamDataGrid; no other types.  I hope this helps.

What is the ultimate goal that you want to achieve?

This isn't the issue i'm having - 

If you run the attached project you'll see that the select row count is wrong when right clicking on additional rows - so with one row selected, right clicking on a different row will print out '1' to the project output when it should be 2.

regards

I see where the problem is. The SelectionChanged event will fire for all the types of objects that can be selected in the XamdataGrid - Cells, Fields, Records. So, what you need to do is check the e.Type property and see which type is being selected:

if (e.Type == typeof(Record))

it looks like the SelectionChanged event is  fired but the SelectedItems collection doesn't contain the correct count of rows.

I have attached a sample showing this