“Please send us a sample project”
If you have contacted Telerik’s support before, chances are that you have been asked to send us a sample project. In our daily routine, we try to avoid requesting such as much as possible, but there are cases in which we simply cannot move forward without a project that would allow us to reproduce a specific problem locally. We usually ask for isolated sample only after:

• we have failed to reproduce the reported problem by following your instructions
• we have failed to reproduce the reported problem by running the code provided
• we have failed to reproduce the reported...

With our still hot Q3 2009 release we introduced a brand new RadCoverFlow control, that was rewritten from scratch in order to be able to exploit some new features in Silverlight 3 that improved both its performance and appearance. We are now using matrix projections to transform the items’ content and pixel shader effects to render the reflection. This allows us to show and properly transform any element in RadCoverFlow, including UI Elements, controls and video, as well as instantly synchronize the reflection.

This major change in the control caused major changes in its API and usage patterns. We provide some...

In some scenarios it is required to load thousands of items in a ComboBox. Since by default the control creates RadComboBoxItem containers for each data item, it might take some time to open the drop-down. To resolve the problem you only need to change the RadComboBox ItemsPanel with VirtualizingStackPanel:

<telerikInput:RadComboBox> <telerikInput:RadComboBox.ItemsPanel> <ItemsPanelTemplate> <VirtualizingStackPanel /> </ItemsPanelTemplate> </telerikInput:RadComboBox.ItemsPanel> </telerikInput:RadComboBox>

 

thus making the drop-down to open instantly.

Attached is a simple application that loads 1000 items in two RadComboBox controls, one virtualized, the other – not virtualized. The difference between the two controls is visible and becomes much larger if you create 100,000 items!

I hope this helps....

Sometimes, when a button is clicked we want to display a drop-down menu with options. This is handy interface, usually present in toolbars, but sometimes - as standalone buttons, like the Save As button in the the VS2008 Save As dialog. Sometimes the drop-down buttons consist of two parts – action and menu, and are called split buttons. In this post I will demonstrate how to achieve the drop-down menu button part. If you need a split button, just add another button and keep track of what was the last clicked menu item. Note, that with Q3 2009 we will...

In my previous article on the same topic I described how to replace the ItemsPresenter of RadComboBox with a RadTreeView. It was as simple as updating the control template. Unfortunately the controls’ selection synchronization relied on a bug in RadComboBox that we recently fixed – the control was able to have a value in its SelectedItem property, that was not present in its Items collection. Now, in order to workaround this new problem, we have to either inherit RadComboBox, or create an attached behavior that will allow us to get the SelectedItem of the inner RadTreeView. The code you have to write...

Often we need to display in a TreeView flat, self-referencing data, loaded from a database, that has properties ID and ParentID (or similar) that define the hierarchy. The Telerik TreeView for ASP.NET can automatically bind itself to such data, but our Silverlight TreeView cannot do this out of the box. Fortunately, this “limitation” can be easily avoided with a simple value converter. There is a little trick, however – each data item needs a reference to its parent collection.

Consider the following very simple data object:

public class DataItem : INotifyPropertyChanged
{
    private string text; 

 public int ID { get; set; }
    public int ParentID {...

RadMenu for Silverlight supports simple checkable items, but still does not support radio button items. This feature is scheduled for development and most probably will come with Q3 2009, but until then you have to code it by yourself. Fortunately, this is relatively easy with a proper ViewModel, that contains the radio-button logic:

The CommandItem class contains the properties and the logic for a RadMenuItem. It implements INotifyPropertyChanged and its most important property is IsChecked:

public bool IsChecked
{
    get
    {
        return this.isChecked;
    }
    set
   ...

RadMenu and RadContextMenu for Silverlight cannot automatically scroll their items if their height exceeds a certain height. We are planning to implement this feature in the near future, but at the moment there are two workarounds for the developers: override the RadMenu control template and add ScrollViewer controls around the ItemsPresenters, or customize the ItemsPanel of the RadMenuItem controls, so the sub-items are displayed in columns. The second option is much easier and looks good enough:

The main idea is to replace the RadMenuItem ItemsPanel, that is a StackPanel by default, with a WrapPanel. To set the ItemsPanel property of all...

A common request in our support is to display a combo box, containing all values of a specific Enum. This is fairly easy with RadComboBox for Silverlight - all you need to do is to fill its ItemsSource collection with the Enum values. The best way to do this is to create a view model for the Enum:

using System;
using System.Collections;
using System.Linq;
using System.Reflection;

namespace SilverlightApplication1
{
    public class EnumModel
    {
        private Type enumType;

        public IEnumerable Values { get; private set; }

        [TypeConverter(typeof(TypeTypeConverter))]
    ...

The RadWindow control is part of the Telerik’s RadControls for ASP.NET AJAX suite and is intended to replace the standard browser’s popup (window.open()). Since the control is based on an IFRAME, it behaves just like one – basically, whatever can be done with an IFRAME, can be achieved with RadWindow as well. This fact is useful when you investigate a reason for some problem related to the RadWindow control. Just replace the RadWindow with a standard IFRAME or browser’s popup and see how your application will behave in this case. If the problem still exists, then it is not related to the...