Last Updated: 04 Dec 2020 14:22 by ADMIN
1.The editor overlapping other cells after editing.

2. The arrow, that is actually meant to open the DropDown, cannot be clicked. Only the cell under it is clicked instead.
Last Updated: 04 Dec 2020 10:11 by ADMIN

When you are using interactive forms in RadPdfViewer, 

https://docs.telerik.com/devtools/winforms/controls/pdfviewer/features/interactive-forms , the editor's font is too big on >100% DPI scaling:

100% looks OK:


Last Updated: 04 Dec 2020 08:14 by ADMIN
Release R3 2017
Use attached project and the following steps:
- When the application starts, use the drop down calendar to select another date.
- Then press Ctrl+A to select the entire content of the editor and press the Del key to clear the content.
- Now press the right arrow key and it crashes with a NullReferenceException inside of the RadDateTimePickerElement.OnKeyDown method.
-  This bug only occurs when ShowCheckBox is true.

class MyRadDateTimePicker : RadDateTimePicker
    protected override RadDateTimePickerElement CreateElement()
        return new MyRadDateTimePickerElement();
class MyRadDateTimePickerElement : RadDateTimePickerElement
    protected override void OnKeyDown(KeyEventArgs e)
        var provider = this.TextBoxElement.Provider as MaskDateTimeProvider;
        if (e.KeyCode == Keys.Right && provider.List != null)

    protected override Type ThemeEffectiveType
            return typeof(RadDateTimePickerElement);
Last Updated: 04 Dec 2020 08:13 by ADMIN
Release R3 2018 SP1
To reproduce: Add a RadMultiColumnCombobox to the form, set the DropDownStyle property to DropDownList and clear the text. You will notice that the height of the control is not bigger than 5 px.

Workaround: set MinimumSize 

Me.RadMultiColumnComboBox1.MinimumSize = New Size(200, 23)

Last Updated: 04 Dec 2020 08:12 by ADMIN
Release R1 2021 (LIB 2020.3.1102)
Created by: Wardeaux
Comments: 5
Category: FileDialogs
Type: Bug Report

Dear sirs,

 i am using the RadFileExplorer control within my Winforms application. I experience exceptions with the stock control from within your demo application using this control.

See attached animated GIF

Steps to reproduce:

1) open a Windows file explorer and browse to any folder like E:\TEMP

2) Create two empty folders in the target destination of E:\TEMP

3) open the winforms demo app and open the "File Dialogs" screen. Open the RadFileExplorer sample

4) browse to the same location as your File Explorer (like E:\TEMP) where you created the new folders

5) from within the RadFileExplorer control, delete one of the folder. all works well

6) In the Windows File Explorer, create a new folder. It will appear within the RadFileExplorer display.

7) close the RadFileExplorer demo screen, reopen the RadFileExplorer demo screen

8) browse to the same location as before (E:\TEMP)

9) From within either the RadFileExplorer control OR the Windows File Explorer delete the new folder created in set 6 above

** Exception: "Changing Children Collection of an already disposed element"

Last Updated: 03 Dec 2020 12:09 by ADMIN
After a hyperlink is edited in a RTF document it duplicated
In Development
Last Updated: 02 Dec 2020 15:45 by ADMIN

Clicking on a tab item in the design surface should select the tab. The animation demonstrates the current behavior:

In Development
Last Updated: 02 Dec 2020 15:42 by ADMIN

Please refer to the attached gif file.

Note: the developer should be able to select a tab at design time and add groups and items to each tab. Currently, a different tab can't be selected.

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 14:34 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.
Last Updated: 01 Dec 2020 07:43 by ADMIN

Please refer to the attached gif file.

Workaround: set bottom padding by setting the SyntaxEditorElement.HorizontalScrollBar.Padding property. 

mySyntaxEditor1.SyntaxEditorElement.HorizontalScrollBar.Padding = new Padding(0, 0, 0, 2);

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

See attached screenshot. The popup calendar looks wrong when running on a display with 250% scaling. Surely, that's not correct. The calendar should not be so large and the fonts so small. Am I missing something? I have done all the other steps to enable High DPI support, and as you can see, the textbox area seems to scale fine.

Any ideas?


Last Updated: 30 Nov 2020 14:53 by ADMIN
Created by: Mihajlo
Comments: 3
Category: ImageEditor
Type: Bug Report
Create a new blank Telerik project. Add RadImageEditor control to the form. Start the app. Open some jpg image. Try to save this image in various formats. No matter what format you select, from BMP to TIFF, the image will be saved in PNG format. The file extension will be .bmp or .tiff, but the file contents is PNG.
Need More Info
Last Updated: 30 Nov 2020 14:51 by ADMIN
Created by: Guy
Comments: 1
Category: GridView
Type: Bug Report

i am getting a null reference exception with the following call stack:


Description: The process was terminated due to an unhandled exception.

Exception Info: System.NullReferenceException

   at Telerik.WinControls.UI.TableViewRowLayoutBase.GetRowHeight(Telerik.WinControls.UI.GridViewRowInfo)

   at Telerik.WinControls.UI.RowElementProvider.GetElementSize(Telerik.WinControls.UI.GridViewRowInfo)

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].GetScrollHeight(System.__Canon)

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].ScrollDown(Int32)

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].ScrollTo(Int32)

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].scrollbar_ValueChanged(System.Object, System.EventArgs)

   at Telerik.WinControls.UI.RadScrollBarElement.OnValueChanged(Int32, Int32)

   at Telerik.WinControls.UI.RadScrollBarElement.set_Value(Int32)

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].UpdateScrollValue()

   at Telerik.WinControls.UI.ItemScroller`1[[System.__Canon, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089]].UpdateScrollRange()

   at Telerik.WinControls.UI.RowScroller.UpdateScrollRange()

   at Telerik.WinControls.UI.GridTableElement.UpdateNoDataText()

   at Telerik.WinControls.UI.GridTableElement.UpdateAll()

   at Telerik.WinControls.UI.GridTableElement.UpdateViewCore(System.Object, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.GridTableElement.UpdateView(System.Object, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.GridTableElement.ProcessTemplateEvent(Telerik.WinControls.UI.GridViewEvent)

   at Telerik.WinControls.UI.GridTableElement.Telerik.WinControls.UI.IGridViewEventListener.ProcessEvent(Telerik.WinControls.UI.GridViewEvent)

   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessCollection(Telerik.WinControls.UI.GridViewEvent, Telerik.WinControls.UI.PriorityWeakReferenceList, Telerik.WinControls.UI.GridEventProcessMode)

   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessEvent(Telerik.WinControls.UI.GridViewEvent)

   at Telerik.WinControls.UI.GridViewSynchronizationService.NotifyListeners(Telerik.WinControls.UI.GridViewEvent)

   at Telerik.WinControls.UI.GridViewSynchronizationService.FlushEvents()

   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(Telerik.WinControls.UI.GridViewEvent)

   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(Telerik.WinControls.UI.GridViewTemplate, Telerik.WinControls.UI.GridViewEvent, Boolean)

   at Telerik.WinControls.UI.GridViewTemplate.DispatchEvent(Telerik.WinControls.UI.GridViewEvent, Boolean)

   at Telerik.WinControls.UI.GridViewTemplate.DispatchDataViewChangedEvent(System.Object, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.GridViewTemplate.OnViewChanged(System.Object, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.MasterGridViewTemplate.OnViewChanged(System.Object, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.GridViewTemplate.EndUpdate(Boolean, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.MasterGridViewTemplate.EndUpdate(Boolean, Telerik.WinControls.UI.DataViewChangedEventArgs)

   at Telerik.WinControls.UI.GridViewTemplate.set_RowCount(Int32)

   at Telerik.WinControls.UI.RadGridView.set_RowCount(Int32)

   at Communication_Logger.frmCommunicationLogger.RadRibbonForm1_OnDataReceived(Communication_Logger.Data)

   at Communication_Logger.ChannelClass.Serial_DataReceived(System.Object, System.IO.Ports.SerialDataReceivedEventArgs)

   at System.IO.Ports.SerialPort.CatchReceivedEvents(System.Object, System.IO.Ports.SerialDataReceivedEventArgs)

   at System.IO.Ports.SerialStream+EventLoopRunner.CallReceiveEvents(System.Object)

   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(System.Object)

   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)

   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)

   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()

   at System.Threading.ThreadPoolWorkQueue.Dispatch()

   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()


the setup is a dotNet 4.5.2 winforms application with RadGridView in virtual mode.

The exception occur when the application is left working for days (2 in this case) without any user interaction.

The application normally updates a list that is used by the gridview, the list records are added and removed continuously, the grid view RowCount is updated via a timer.

i suspect that the RowCount reported at one point in time doesn't match the list size as it is trimmed, and therfore the GetRowHeight fails as the data doesn't exist - can this be handled in the gridview - to avoid a termination of the process due to the exception ?





Last Updated: 30 Nov 2020 14:43 by ADMIN
Created by: Yusi
Comments: 4
Category: PropertyGrid
Type: Bug Report

Problem: I'd like to filter the properties to be displayed by their category names defined by the Category attribute. Based on the doc here (https://docs.telerik.com/devtools/winforms/controls/propertygrid/features/filtering), my understanding is to add a FilterDescriptor like this: New FilterDescriptor ("Category", FilterOperator.Contains, "some category name"). But it turned out to only filter by property name, not category name. Any misunderstanding or possible issue? Thank you for looking into this.


1. Define a class like this:

    Private Class TestClass
        <Category("Cat1")> Public Property Property1 As Integer = 1
        <Category("Cat1")> Public Property Property2 As String = "Test 2"
        <Category("Cat2")> Public Property Property3 As String = "Test 3"
    End Class

2. Initialize a RadPropertyGrid in the Form.Load event:

        Dim testObj As New TestClass
        RadPropertyGrid1.EnableFiltering = True
        Dim filter As New FilterDescriptor("Category", FilterOperator.Contains, "2")
        RadPropertyGrid1.SelectedObject = testObj

3. The right property to be displayed should be Property3, but it turned out to be Property2


Example project: attached.

Thank you team!


Last Updated: 30 Nov 2020 14:31 by ADMIN

Please refer to the attached gif file illustrating better how to replicate the undesired behavior.

1. If you right-click, the Copy and Cut context menu items are disabled - OK

2. If you select some text and right-click, the Copy and Cut context menu items are enabled - OK.

3. If you select some text and right-click very fast, sometimes Copy and Cut are disabled. Even there is cases in which Cut is enabled and Copy is disabled. 

Workaround: please ensure that you select the text first and then right-click to trigger the context menu.

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