Need More Info
Last Updated: 06 Feb 2023 14:00 by Martin
Created by: Martin
Comments: 5
Category: VirtualGrid
Type: Bug Report


  1. Use the code beneath.
  2. Run this form.
  3. 20 records are shown, the "AddNewRow" is shown.
  4. Select all records.
  5. Press <delete>
  6. 0 records are shown (as expected), the "AddNewRow" is invisible (unexpected).
  7. Close the program.
  8. Modify LoadTable(true) to LoadTable(false). Records will not be created..
  9. Run this form.
  10. 0 records are shown (as expected), the "AddNewRow" is invisible (unexpected).

Expected behavior:

  • Even when the dataTable or view has no rows, we should still be able to add new rows.

Observed behavior:

  • When datatable/view is empty, no new records are allowed to enter.

Please observe that Grid.UserAddedRow is not handled, but since we cannot even see the AddNewRow, it is not required for this bug.

	public partial class TestForm: Form
		private readonly DataView _view;

		public TestForm()

			_view = new DataView(LoadTable(true));
			_grid.ColumnCount = _view.Table.Columns.Count;
			_grid.RowCount = _view.Count;
			_grid.AllowAddNewRow = true;
			_grid.SelectionMode = VirtualGridSelectionMode.FullRowSelect;

		static private DataTable LoadTable(bool fill)
			var table = new DataTable();
			table.Columns.Add("Number", typeof(int));
			if (fill)
				for(int i = 0; i < 20; i++)
			return table;

		#region Windows Form Designer generated code

		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
			this._grid = new Telerik.WinControls.UI.RadVirtualGrid();
			// _grid
			this._grid.Dock = System.Windows.Forms.DockStyle.Fill;
			this._grid.Location = new System.Drawing.Point(0, 0);
			this._grid.MultiSelect = true;
			this._grid.Name = "_grid";
			this._grid.SelectionMode = Telerik.WinControls.UI.VirtualGridSelectionMode.FullRowSelect;
			this._grid.Size = new System.Drawing.Size(800, 450);
			this._grid.TabIndex = 0;
			this._grid.CellValueNeeded += new Telerik.WinControls.UI.VirtualGridCellValueNeededEventHandler(this._grid_CellValueNeeded);
			this._grid.UserDeletedRow += new Telerik.WinControls.UI.VirtualGridRowsEventHandler(this._grid_UserDeletedRow);
			// TestForm
			this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
			this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
			this.ClientSize = new System.Drawing.Size(800, 450);
			this.Name = "TestForm";
			this.Text = "TestForm";



		private Telerik.WinControls.UI.RadVirtualGrid _grid;

		private void _grid_CellValueNeeded(object sender, Telerik.WinControls.UI.VirtualGridCellValueNeededEventArgs e)
			if (e.ColumnIndex < 0)

			if (e.RowIndex < 0)
				e.FieldName = _view.Table.Columns[e.ColumnIndex].ColumnName;
				if (e.RowIndex == RadVirtualGrid.HeaderRowIndex)
					e.Value = e.FieldName;
			else if (e.RowIndex < _view.Count)
				e.Value = _view[e.RowIndex][e.ColumnIndex];

		private void _grid_UserDeletedRow(object sender, Telerik.WinControls.UI.VirtualGridRowsEventArgs e)
			var rowIndexes = e.RowIndices.Distinct().OrderByDescending(i => i).ToList(); // Off topic: I have seen duplicate row indexes in this row collection. And unsorted. Is that by design?
			if (rowIndexes.Count == _view.Count)
				foreach(var index in rowIndexes)

			_grid.RowCount = _view.Count;

Need More Info
Last Updated: 13 Jan 2023 11:31 by ADMIN
Created by: kieran
Comments: 1
Category: TimePicker
Type: Bug Report

Hi there.

Selecting a time from the TimePicker sets the time.  However, if the bound parameter is null, the Date part of the DateTime values are still invalid and will throw errors when saving data to databases.

The TimePicker should at least by default insert a default valid Date even if it is 01/01/1900 or DateTime.Today.

Regards Kieran.


Need More Info
Last Updated: 30 Nov 2022 05:59 by ADMIN

I can't provide a project or even code snippets that would make sense out of context because the code base is too complex for an easy replication to be setup.

We are trying various things like calling Refresh, Update.


Hoping this is something you've encountered before and have some suggestions.

Need More Info
Last Updated: 22 Sep 2022 06:06 by ADMIN

C#. net core 6, winforms application, TekerikNuGet3 package source, UI.for.WinForms.AllControls.NetCore package 2022.2.622

I am trying to export selected cells from a RadGridView as a csv file.

When using "var exporter = new ExportToCSV(Dgv)" then "exporter.RunExport(fileName);" writes the csv file correctly. It exports every cell.

It doesn't support exporting selections so I wrote a function to do this . The one below is what I used in my project to test what I was doing. It initially writes the csv to a worksheet and wrote that using formatprovider to file, then I just created a stringbuilder adding quotes and appended that to the file afterwards.

Writing the worksheet, the csv values haven't been quoted, plus number fields have had leading zeros removed which proves to be a problem when telephone numbers are stored in a field.

So I googled and found the Settings property which is there to set csv options. But they are private, not public therefore I can't set up the csv propertly.

private void radButton1_Click(object sender, EventArgs e)

    var workbook = new Workbook();
    var worksheet = workbook.Worksheets.Add();

    var rowIndex = 0;
    var columnIndex = -1;
    var sb = new StringBuilder();
    var prevColumnIndex = -1;

    // ForEach cell are accessed vertically then horizontally.
    foreach (var cell in Dgv.SelectedCells)
      // Cell is included in selection even if it's invisible
      // so check visibility and ignore if it isnt
      if (!cell.ColumnInfo.IsVisible) continue;

      // At bottom of column, rownum will change. Watch for this
      // and reset x and y values
      var rowNum = cell.RowInfo.Index;
      if (rowNum != prevColumnIndex)
        prevColumnIndex = rowNum;
        rowIndex = 0;
      else if (!string.IsNullOrEmpty(sb.ToString()))

      var value = cell.Value;
      worksheet.Cells[columnIndex, rowIndex++ ].SetValue(value.ToString());

    var fileName = @"C:\temp\SampleFile.csv";

    IWorkbookFormatProvider formatProvider = new CsvFormatProvider();
    using var output = new FileStream(fileName, FileMode.Create);
    formatProvider.Export(workbook, output);

    // Write contents of sb to the file for comparison sake
    File.AppendAllText(fileName, sb.ToString());


Need More Info
Last Updated: 03 Aug 2022 12:11 by ADMIN

I just upgraded to the latest version of Telerik products and facing the issues described below.

When dragging and drop Telerik UI objects from the toolbar on a form, the dialog box below is displayed with question but there is no button to click to answer the question and I don't where to stop it.

See screenshot attached.

Need More Info
Last Updated: 26 May 2022 06:20 by ADMIN
It would be nice if the grid column chooser would support grouping of columns similar to the jquery grid
Need More Info
Last Updated: 10 Mar 2022 08:52 by ADMIN
Created by: Ian
Comments: 1
Category: UI for WinForms
Type: Feature Request

GridView has a default text alignment for new columns as 'MiddleCenter'.

Default alignment for new GridViewDataRowInfo is 'left'.

Please can these be the same ?

Need More Info
Last Updated: 18 Feb 2022 08:53 by ADMIN
Created by: MrBizzl
Comments: 7
Category: Installer and VS Extensions
Type: Bug Report

Dear Ladies and Gentlemen

Currently I am trying in vain to upgrade to the latest version Telerik UI for WinForms 2022.1.118.
However, the update fails with the error given below.

I have already uninstalled and reinstalled VS2019. Unfortunately this did not help.

Can you help?

Best Timo

Need More Info
Last Updated: 15 Feb 2022 14:48 by ADMIN
Created by: Ian
Comments: 1
Category: ChartView
Type: Feature Request
Some other charting frameworks support ‘dynamic’ graphs/diagrams, where the graph shows nodes and links, and the user can drag the nodes around the page, and the other nodes are pulled around it. This is a great way to visualise and explore this kind of node+link data. Its also a great way to sell and app, as it looks cool.
Need More Info
Last Updated: 28 Jan 2022 09:03 by ADMIN
Created by: Haithem
Comments: 1
Category: PdfViewer
Type: Bug Report



I am have a problem with pdf wiewer when the PDF file contains an images , it is slow in movement and it is difficult to navigate between pages. Is it possible to fix this problem 



Need More Info
Last Updated: 02 Dec 2020 14:48 by ADMIN

Hi All,

Note:- I am using Bound RadTreeview. Bound with DataSource.

1 Take RadTreeview

2 Add Few nodes Like:

    ......Node A

    ......Node B

    ......Node C

    ............Node D

    ............Node E

3 Now Drag Node B and Drop it in Node C (As Node C's Child)

4 It throw Exception Error Msg  "Collection was modified; enumeration operation may not execute."

5  Now Try to Drag Node E and Drop it in Node B, again same error occurs

6 Full error screen i attached here.

Please reply as soon as possible.


Need More Info
Last Updated: 02 Dec 2020 14:37 by ADMIN
Created by: avani
Comments: 1
Category: TreeView
Type: Bug Report

Hi All,


I have made User control for custom node, in this user control i have used following controls

1 RadLabel (no of control - 3)

2 RadPanel (no of control -1)

3 PictureBox (no of Control - 4 )

4 TableLayoutPanel (no of control -3)

Means i have used total 11 controls within my user control.

Height of usercontrol = 146

Width of Usercontrol = 595


I have taken RadTreeView and above UserControl added as Node,following properties of treeview is set

this.radTreeView1.DataSource = Staff.GetStaff();
            this.radTreeView1.ParentMember = "ParentID";
            this.radTreeView1.ChildMember = "ID";
            this.radTreeView1.DisplayMember = "Department";
            this.radTreeView1.CreateNodeElement += this.OnCreateNodeElement;

this.radTreeView1.TreeViewElement.AutoSizeItems = true;
            this.radTreeView1.ShowRootLines = false;
            this.radTreeView1.FullRowSelect = false;
            this.radTreeView1.ShowLines = true;
            this.radTreeView1.LineStyle = TreeLineStyle.Solid;
            this.radTreeView1.LineColor = Color.FromArgb(110, 153, 210);
            this.radTreeView1.TreeIndent = 50;



But when i run the code it shows like this means my control is not displaying and the property "AutoSizeItems" is not working.


hope for quick reply

Need More Info
Last Updated: 02 Dec 2020 14:36 by ADMIN

Hello Guys,


Good Evening , As per your suggestions i make my custom treeview node with LiteVisualElements .

In That Node i have taken one StackLayoutElement and RoundRectShape assigned to it but still panel shows corners instead of round edges,

i tried with different properties and styles but not get succeed , so please help me out.

here i have attached image of my node and "stackLayoutElement" code too.

spnlControls = new StackLayoutElement();
            spnlControls.Orientation = Orientation.Horizontal;
            spnlControls.NotifyParentOnMouseInput = true;
            spnlControls.DrawFill = true;
            spnlControls.DrawBorder = true;
            spnlControls.Shape = new RoundRectShape(4);
            spnlControls.BackColor = Color.Transparent;
            spnlControls.BackColor2 = Color.Transparent;
            spnlControls.BackColor3 = Color.Transparent;
            spnlControls.BackColor4 = Color.Transparent;
            spnlControls.BorderGradientStyle = GradientStyles.Solid;
Need More Info
Last Updated: 02 Dec 2020 14:35 by ADMIN
Created by: Kaan
Comments: 1
Category: UI for WinForms
Type: Feature Request


I want to hide some columns of the table I received from Excel on RadGridView.

Need More Info
Last Updated: 02 Dec 2020 14:34 by ADMIN
Created by: Larry
Comments: 1
Category: RichTextEditor
Type: Bug Report
There appears to be an issue when adding Comments that overlap each other. I will attach a video to my next reply that shows how to replicate the issue.
Need More Info
Last Updated: 02 Dec 2020 14:33 by ADMIN
Fatching data from sql database in gridViewCommboBoxColumn select the value then retrieve data other column in the same Rows windows application in
Need More Info
Last Updated: 30 Nov 2020 14:59 by ADMIN
The filter UI controls in ASP.NET Core and MVC are really nice, see filter. Can you include the same controls and UI be included in Winforms and WPF?
Need More Info
Last Updated: 30 Nov 2020 14:59 by ADMIN
Created by: Mario
Comments: 3
Category: UI for WinForms
Type: Feature Request

Hi everybody


I m try use the class CustomDragandDrop on radtreeview but i have a issue, 

if i use the next example, i dont have any problem:


   protected void BindRadTreeView()
            DataTable dt = new DataTable();
            dt.Columns.Add("Id", typeof(string));
            dt.Columns.Add("Title", typeof(string));
            dt.Columns.Add("ParentId", typeof(string));

            string parentId = string.Empty;
            string childId = string.Empty;
            for (int i = 0; i < 2; i++)
                parentId = Guid.NewGuid().ToString();
                dt.Rows.Add(parentId, "Node" + i, null);
                for (int j = 0; j < 5; j++)
                    childId = Guid.NewGuid().ToString();
                    dt.Rows.Add(childId, "SubNode" + i + "." + j, parentId);

            this.radTreeView1.ChildMember = "Id";
            this.radTreeView1.ParentMember = "ParentId";
            this.radTreeView1.DisplayMember = "Title";
            this.radTreeView1.DataSource = dt;



i can drag and drop correctly


but the problem is when i binding the Radtreeview



    protected void llenatreeview1() {

            dtTablas = dat.consultaBD();

            DataTable dt = new DataTable();
            dtCopi.Columns.Add("Id", typeof(string));
            dtCopi.Columns.Add("Title", typeof(string));
            dtCopi.Columns.Add("ParentId", typeof(string));

            string parentId = string.Empty;
            string Id = string.Empty;
            string title = string.Empty;
            foreach (DataRow row in dtTablas.Rows)
                parentId = row["ParentId"].ToString();     

                Id = row["Id"].ToString();
                title = row["Title"].ToString();

                if (parentId == "")
                    dt.Rows.Add(Id, title, null);
                    dt.Rows.Add(Id, title, parentId);

            radTreeView2.ChildMember = "Id";
            radTreeView2.ParentMember = "ParentId";
            radTreeView2.DisplayMember = "Title";
            radTreeView2.DataSource = dt;

first is freeze and then appears the error.

when i drag and drop appears then next error:



what am I doing wrong please your help. thanks
Need More Info
Last Updated: 30 Nov 2020 14:58 by ADMIN
Created by: Robyn
Comments: 1
Category: UI for WinForms
Type: Bug Report

Hi there,


We have recently found a bug on both the RadDocument and Rad Rich Text Editor. Created a RTF document via the RadRichText Editor. The RTF document contains a table. When the document is saved and loaded from the same form, it is displaying correctly, however when loaded from a different form, it seems to have shrunk and lost the column width, thus having long and skinny columns.

We have set the fixed column width on the table, however this did not seem to solve the issue.

I have attached two screenshots for reference. One with the correct looking table, and one with the long and skinny columns.

Is there a workaround, or is this a known bug?


Correct table:



Long and skinny columns:


Currently on Telerik Winforms version 2018.3.1016.40


Kind regards,



Need More Info
Last Updated: 30 Nov 2020 14:55 by ADMIN

I have a form which contains TreeView control. I need to convert it to RadTreeView. So I replaced TreeView control with RadTreeView and TreeNode with RadTreeNode in the code. I found that the events in both are different, so tried to replace the events with similar events in RadTree.

Following are the events that I have replaced in my code :


        Private Sub TreeView1_AfterExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles tvMain.AfterExpand

Replaced by -

        Private Sub TreeView1_AfterExpand(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.RadTreeViewEventArgs) Handles tvMain.NodeExpandedChanged   


            Private Sub TreeView1_AfterCollapse(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles tvMain.AfterCollapse

  Replaced by -  

            Private Sub TreeView1_AfterCollapse(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.RadTreeViewEventArgs) Handles tvMain.NodeExpandedChanged

and included Expanded flag to check if it is expand or collapse.

Here, I noticed unwanted firing of this replaced event when compared to the old event, but I handled it using the Expanded flag.


        Private Sub tvMain_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles tvMain.AfterSelect

Replaced by -

        Private Sub tvMain_AfterSelect(ByVal sender As System.Object, ByVal e As Telerik.WinControls.UI.RadTreeViewEventArgs) Handles tvMain.SelectedNodesChanged

This event gets fired twice while clicking on a node.

My main issues are,

  • During the initial load of the form, the tree gets populated and at that time the select event (mentioned in point 3) fires automatically in my old project in which TreeView is used. But in the new project, during the load of the form the replaced event is not fired.
  • Similarly, when I clicks a node , the replaced select event fires twice. After that I have a button in the same form which works like, when we click on a node and then click on the add button it will add a new node to the tree under the selected node. Now the functionality of the button doesnt work because, within the click function of add button, treeView1.selectedNode is 'Nothing'. Eventhough the select event is fired on clicking the node, the selectednode is 'Nothing' inside the click function of add button.
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