Problems migrating to DragDropManager with TreeView

2 posts, 0 answers
  1. Ralf
    Ralf avatar
    1 posts
    Member since:
    Apr 2014

    Posted 14 Apr 2014 Link to this post


    I've written a custom control containing a RadTreeView to encapsulate the logic to handle drag&drop because I need this in multiple places in my application. This control used the RadDragAndDropManager. My current task is to migrate to DragDropManager and started this by disable the old drag&drop handlers and set the drag drop execution mode:

            public override void OnApplyTemplate()
                if (_treeView != null)

                _treeView = GetTemplateChild(TreeViewName) as RadTreeView;
                if (_treeView != null)
                    TreeViewSettings.SetDragDropExecutionMode(_treeView, TreeViewDragDropExecutionMode.New);

    So far so good. This compiles without errors but soon I start to drag I get the following error from the browser:

    Line: 57
    Error: Unhandled Error in Silverlight Application 
    Code: 2512    
    Category: ParserError       
    Message: Failed to create a 'System.Windows.Media.Brush' from the text 'Null}'.     
    Line: 6534     
    Position: 48     

    I have no cue that could be the cause of the problem. The VS debugger does NOT stop or throws any exception. If I use the old drag&drop execution mode I have no problems. ​I use 2013.3.1104.1050 of the Telerik assemblies.
    Must I handle all drag&drop events to make this work or is this a problem in the Telerik controls?

    Thanks for the support!

  2. Pavel R. Pavlov
    Pavel R. Pavlov avatar
    1251 posts

    Posted 17 Apr 2014 Link to this post

    Hello Ralf,

    Thank you for contacting us on that matter. Please note that I cannot be sure about your particular implementation. Hence, I am unable to reproduce and test the reported behaviour on our side.

    However, you may find helpful our DragDropManager Migration article. Also, with the new drag drop logic we exposed the TreeViewDragDropOptions object. It exposes properties that control the visual feedback when you perform drag&drop operations in the RadTreeView control. You can find more information in our How To -> Drag and Drop section of our tree view documentation.

    If these articles are not helpful in your particular case. I will need you to provide me with additional information about your implementation. I need to reproduce the issue on our side in order to investigate the reasons behind it and suggest an approach.

    Thank you for understanding.

    Pavel R. Pavlov

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

Back to Top