Custom filtering for Enum types, TypeConverter support for business object bind to RadGridView

I am executing the following code.  Utilizing the debugger I know the code is only implemented once, and it works correctly at first but then at seemingly random intervals multiple rows will expand.   I used modified code as well to first collapse all rows and then expand only the one with the matching ID field, but I get the same results.

Gridview contains one image column and one text column. It is supposed that the data in the gridview is sorted by the text column. EnableSorting is enabled for the whole gridview. The image column has AllowSort disabled and SortOrder set to None whereas the text column has the SortOrder set to Ascending. However, if the grid is populated with data it is primarily sorted by the image column. 
This problem is illustrated in the attached project. I've added three rows with data and would expect the grid be sorted as "A", "B", "C", whereas the resulting order is "B", "C", "A" due to the image in the row which contains the "A".

We would like to use the expressions created using the GridView in some of our LINQ queries on the individual columns. Are we able to get the raw C# or LINQ expression format from the expression editor for the actual expression? What language does the expression essentailly compile to?

The recommended solution works fine but late I found that unfortunately there is some error in handling custom filters that prevents in most of our grids correct functioning. 
I enabled custom filtering and assigned event handler. When following conditions are met:
    - grid has no FilterDescriptors
    - e.Handled is set to false in GridViewCustomFilteringEventHandler

then row, for which was set e.Handler = false in custom filtering event handler, is not shown in the grid. If grid has some FilterDescriptor in its FilterDescriptors collections, then everything works as expected.

The setup of ExpressionFormattingObject for inner GridViewTemplate not apply the conditional formatting to children rows

Run the enclosed application and select the funnel icon in most right column "AKTIV" and select menu item "No filter". The application crashes. If you do the same using checkbox in filter cell, everything works fine.

Wrong column name escaping in filter expression when the special symbols is used in the name like: "_x0000_", "_x0032_0", "_x0032_0_x0000_"  in the bound data schema

After the delete, the item is removed from the BindingList, but it still appears in the RadGridView (or deleted a wrong item). The binding doesn't trigger the change in the UI/View.

change the localization provider for one gridview only (e.g. we have multiple different grids in our application, but I want to apply that custom RadGridLocalizationProvider selectively to only few of them)

GridView “decimal column -          Current value “500”-          Input “1.2.3.4” Scenario case: 1.       Approaching to the target cell by “Mouse click directly on the input cell” then key in “1.2.3.4” and Enter à Display “500” as original value2.       Approaching to target cell by “Tab or moving cursor to input cell” then key in “1.2.3.4” and Enter à Display “1” as only display the first input digit only

has no user validation, exception when the type of parent and child keys is different

Advanced Property Grid in Property Builder filter the data source list and not show 'Project Data Sources' for selection in the DataSource popup.

There is a difference in the drop down Datasource selection between the :
    GridviewDataColumn Collection Editor      and the...
    RadGridView Property Builder

The RadGridView is bound to DataView

Workaround: add row using the DataTable API:
private void radButton1_Click(object sender, EventArgs e)
{
    DataRow row = m_dvMat.Table.NewRow();
     row["Active"] = true;
     row["Category"] = form.m_sString;
     m_dvMat.Table.Rows.Add(row);
}

After updating a cell, the RowsChanged event fires 3 times

Please view the related project. The issue is valid when Sort API of Column object is used or sorting is added from SortDescriptors.Add method.

"IsContainedIn" and "IsNotContainedIn" operators currently not work properly with composite values like: "1, 2, 3"

The following code exhibits the problem. All you have to do is click the Wrapper column cell and bring down the dropdown. Then select the Phase column. You will get the app to crash in the FilterWrappers method.

namespace RadControlsWinFormsApp2
{
    public partial class Form1 : Form
    {
        private String[] dataPhases = null;
        private String[] dataWrappers = null;
  
        public class Data
        {
            public Data(int ID, string Phase, int Wrapper)
            {
                this.ID = ID;
                this.Phase = Phase;
                this.Wrapper = Wrapper;
            }
            public int ID { get; set; }
            public String Phase { get; set; }
            public int Wrapper { get; set; }
        }
        public Form1()
        {
            InitializeComponent();
  
            this.radGridView1.DataSource = new Data[] { new Data(1, "A", 1), new Data(2, "B", 2) };
        }
  
        private void Form1_Load(object sender, EventArgs e)
        {
            GridViewComboBoxColumn columnPhase = radGridView1.Columns["PHASE"] as GridViewComboBoxColumn;
            dataPhases = new String[] { "A", "B", "C", "A/B/C" };
  
            GridViewComboBoxColumn columnWrapper = radGridView1.Columns["WRAPPER"] as GridViewComboBoxColumn;
            dataWrappers = new String[] { "", "1", "2" };
  
            columnWrapper.DataSource = dataWrappers;
            columnPhase.DataSource = dataPhases;
        }
  
        private void radGridView1_CellEditorInitialized(object sender, Telerik.WinControls.UI.GridViewCellEventArgs e)
        {
            if (e.Column is GridViewComboBoxColumn)
            {
                RadDropDownListEditor editor = e.ActiveEditor as RadDropDownListEditor;
                if (editor != null)
                {
                    RadDropDownListEditorElement editorElement = (RadDropDownListEditorElement)editor.EditorElement;
                    editorElement.Filter = null;
                }
            }
            switch (e.Column.Name)
            {
                case "WRAPPER":
                    {
                        GridViewComboBoxColumn cbc = e.Column as GridViewComboBoxColumn;
                        cbc.DataSource = dataWrappers;
  
                        RadDropDownListEditor editor = e.ActiveEditor as RadDropDownListEditor;
                        if (editor != null)
                        {
                            RadDropDownListEditorElement editorElement = (RadDropDownListEditorElement)editor.EditorElement;
                            editorElement.Filter = FilterWrappers;
                        }
                    }
                    break;
                case "PHASE":
                    {
                        GridViewComboBoxColumn cbc = e.Column as GridViewComboBoxColumn;
                        cbc.DataSource = dataPhases;
                    }
                    break;
            }
        }
  
        private bool FilterWrappers(RadListDataItem item)
        {
            int nWrapper = 0;
            if (item.Value.ToString() != String.Empty)
                nWrapper = Convert.ToInt32(item.Value);
            return true;
        }
    }
}

The problem exist if Column.Remove() is executed for master level.

If you go to The Demos >> Grid View >> Performance >> Load 50,000 rows. And then drag the group to group by the first two columns, then editing cells is slow.