Thank you Maria, After reviewing your example I think the best approach for me is to not put two editable controls in a single column because tabing just doesn't work.  I will continue to work on this, will no doubt have further questions.

Regards,

Sam

Andrew thank you very much for your code, it works great!  I could not have done it myself, thanks again.

Well I think the slowness you mention is because you're using UnboundField for those fields you added to use the ControlHostEditor. BTW since you weren't specifying any Binding or BindingPath for the UnboundField it was showing up blank. In your case it doesn't seem like there is any reason to use an UnboundField - just use Field as you were before but use the ControlHostEditor for the editor.

Another slowness is going to come from the fact that your SelectorTextBox basically makes a copy of the ItemsSource collection (in the Loaded handler) and since you're showing that always that is going to be slow with your 100,000 items. If you don't need to do any mapping of id to value then you might want to consider leaving only the EditDataTemplate and not setting the Template of editor to the EditTemplate so the control is only created when it goes into edit mode (and therefore the Loaded of only 1 SelectedTextBox control is fired at a time and only when going into edit mode). If you do need mapping you might still considering doing it some other way - perhaps a ValueToDisplayTextConverter that maps the id to the value using a dictionary or some other efficient lookup/conversion. And actually if you're going to use our filtering ui for those fields (as you are in your sample) then you'll likely need to do something like the ValueToDisplayTextConverter because you'll presumably want the display name in the filtering dropdowns.

BTW the ItemsSource wasn't really working in your sample because you were trying to do an ElementName binding across namescopes. The Style/DataTemplate each have their own Namescope and the Window/UserControl each have their own namescope. The snippet below uses the DataPresenter of the hosting CellValuePresenter to get to the People collection.

ItemsSource="{Binding Path=(local:ControlHostEditor.Editor).Host.DataPresenter.DataContext.People, RelativeSource={RelativeSource Self}}"

        <igDP:XamDataGrid x:Name="grid" DataSource="{Binding Trades}">
            <igDP:XamDataGrid.FieldSettings>
                <igDP:FieldSettings
                        Width="*"
                        AllowRecordFiltering="True"
                        FilterLabelIconDropDownType="MultiSelectExcelStyle"
                        CellClickAction="EnterEditModeIfAllowed"/>
            </igDP:XamDataGrid.FieldSettings>
            <igDP:XamDataGrid.FieldLayoutSettings>
                <igDP:FieldLayoutSettings
                        AllowDelete="True"
                        AllowAddNew="True"
                        AddNewRecordLocation="OnTop"
                        AllowFieldMoving="WithinLogicalRow"
                        AutoGenerateFields="False"
                        HighlightAlternateRecords="True"
                        FilterUIType="LabelIcons" 
                        MaxSelectedRecords="1"/>
            </igDP:XamDataGrid.FieldLayoutSettings>
            <igDP:XamDataGrid.FieldLayouts>
                <igDP:FieldLayout>
                    <igDP:FieldLayout.Fields>

                        <igDP:Field Name="ACCT_NO" Label="Acct No" Width="130">
                            <igDP:Field.Settings>
                                <igDP:FieldSettings>
                                    <igDP:FieldSettings.EditorStyle>
                                        <Style TargetType="local:ControlHostEditor">
                                            <Setter Property="ValueType" Value="{x:Type system:String}" />
                                            <Setter Property="EditDataTemplate">
                                                <Setter.Value>
                                                    <DataTemplate>
                                                        <samsControls:SelectorTextBox 
                                                            SelectedValue="{Binding RelativeSource={RelativeSource Self}, Path=(local:ControlHostEditor.Editor).Value}"
                                                            SelectionChanged="SelectorTextBox_SelectionChanged"
                                                            ItemsSource="{Binding Path=(local:ControlHostEditor.Editor).Host.DataPresenter.DataContext.People, RelativeSource={RelativeSource Self}}"
                                                            DisplayMemberPath="Name" 
                                                            SelectedValuePath="ID"
                                                            SearchTermType="ID"
                                                            ResultsListWidth="400">
                                                        </samsControls:SelectorTextBox>
                                                    </DataTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </igDP:FieldSettings.EditorStyle>
                                </igDP:FieldSettings>
                            </igDP:Field.Settings>
                        </igDP:Field>


                        <igDP:Field Name="ACCT_Name" Label="Acct Name" Width="130">
                            <igDP:Field.Settings>
                                <igDP:FieldSettings>
                                    <igDP:FieldSettings.EditorStyle>
                                        <Style TargetType="local:ControlHostEditor">
                                            <Setter Property="ValueType" Value="{x:Type system:String}" />
                                            <Setter Property="EditDataTemplate">
                                                <Setter.Value>
                                                    <DataTemplate>
                                                        <samsControls:SelectorTextBox
                                                            SelectedValue="{Binding RelativeSource={RelativeSource Self}, Path=(local:ControlHostEditor.Editor).Value}"
                                                            SelectionChanged="SelectorTextBox_SelectionChanged"
                                                            ItemsSource="{Binding Path=(local:ControlHostEditor.Editor).Host.DataPresenter.DataContext.People, RelativeSource={RelativeSource Self}}"
                                                            DisplayMemberPath="Name" 
                                                            SelectedValuePath="ID"
                                                            SearchTermType="Description"
                                                            ResultsListWidth="400">
                                                        </samsControls:SelectorTextBox>
                                                    </DataTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </igDP:FieldSettings.EditorStyle>
                                </igDP:FieldSettings>
                            </igDP:Field.Settings>
                        </igDP:Field>
                    </igDP:FieldLayout.Fields>
                </igDP:FieldLayout>
            </igDP:XamDataGrid.FieldLayouts>

        </igDP:XamDataGrid>

Andrew, thank you for your sample code.  I tried to use it in my project but I cannot get it to work.

In the attached project I have a xamdata grid with four columns, each of which hosts my custom control. 

Issues:

The main problem I would like to fix is the tab key does not move from column to column.  It moves the active row to the next row.  When the grid receives the focus I would like the user to be able to "just start typing".

The grid appears to load much slower after adding the ControlHostEditor class

Note my custom cotrol dispalys up a popup menu  I need to make sure the ControlHostEditor does not handle the tab key and prevent the event from bubling up to my control

I do not understand the bindings in the ControlHostEditor