New to Telerik UI for WinForms? Download free 30-day trial


The preview window is shown when the user hovers the taskbar button of the application with the mouse:

WinForms RadTaskbarButton Thumbnail Preview

Preview Image

This is the main part of the thumbnail representing a small preview of the application. Setting the ClipControl property allows you to focus on a particular control to be used for the preview, e.g. a RadGridView control:

WinForms RadTaskbarButton Thumbnail Preview Control

The ClipRectangle property allows you to specify a specific part of the control to be displayed in the preview.

Note that when the ClipRectangle property is assigned the ClipControl property will be reset.

Thumbnail Buttons

RadTaskbarButton can display buttons in its thumbnail part. Adding buttons to your thumbnail preview will be an excellent enhancement to your application. This way the user can call commands in your application without restoring or activating the application's window. To add thumbnail button, you can populate the ThumbnailButtons collection of the control.

Figure 1: Thumbnail Buttons

WinForms RadTaskbarButton Thumbnail Buttons

Adding Thumbnail Buttons

Telerik.WinControls.Taskbar.RadThumbnailButton radThumbnailButton1 = new Telerik.WinControls.Taskbar.RadThumbnailButton();
Telerik.WinControls.Taskbar.RadThumbnailButton radThumbnailButton2 = new Telerik.WinControls.Taskbar.RadThumbnailButton();

Dim radThumbnailButton1 As Telerik.WinControls.Taskbar.RadThumbnailButton = New Telerik.WinControls.Taskbar.RadThumbnailButton()
Dim radThumbnailButton2 As Telerik.WinControls.Taskbar.RadThumbnailButton = New Telerik.WinControls.Taskbar.RadThumbnailButton()

To add image content to the buttons, you can populate the ThumbnailButtonsImageList collection of the RadTaskbarButton with the required images. Then, you can set the ImageIndex property of each button to the index of image inside the collection.

var images = new ImageList();
images.Images.Add(new Bitmap("../../ProgressIcon.ico"));
images.Images.Add(new Bitmap("../../WinFormsIcon.ico"));
this.radTaskbarButton1.ThumbnailButtonsImageList = images;
this.radTaskbarButton1.ThumbnailButtons[0].ImageIndex = 0;
this.radTaskbarButton1.ThumbnailButtons[1].ImageIndex = 1;

Dim images = New ImageList()
images.Images.Add(New Bitmap("../../ProgressIcon.ico"))
images.Images.Add(New Bitmap("../../WinFormsIcon.ico"))
Me.RadTaskbarButton1.ThumbnailButtonsImageList = images
Me.RadTaskbarButton1.ThumbnailButtons(0).ImageIndex = 0
Me.RadTaskbarButton1.ThumbnailButtons(1).ImageIndex = 1

Note that once thumbnail buttons are added to the TnumbnailButtons collection and submitted to the application, they no longer can be modified. Only can be hidden by setting the Hidden property.

RadThumbnailButton's API

Property Description
Owner Gets the owner of the thumbnail button.
Tag Tag object that can be used to store user data, taht correcposnds to this button.
ImageIndex Gets or sets the image list index value of the image displayed on the button control.
ImageKey Gets or sets the key accessor for the image in the ImageList.
Icon Gets or sets the System.Drawing.Icon displayed in this button.
ToolTip Gets or sets the tool tip text.
Enabled Gets or sets a value indicating, whether the buttons is enabled. If [true] The button is active and available to the user. If [false] The button is disabled. It is present, but has a visual state that indicates that it will not respond to user action.
DismissOnClick When the button is clicked, the taskbar button's flyout closes immediately.
NoBackground Do not draw a button border, use only the image.
Hidden The button is not shown to the user.
NonInteractive The button is enabled but not interactive; no pressed button state is drawn. This value is intended for instances where the button is used in a notification.

Click Event

To distinguish which button is clicked by the user and execute any application logic, you can subscribe to the ThumbnailButtonClick event of the RadTaskbarButton. In the event handler you can get the pressed button from the event arguments.

Non Interactive State

There could be requirement to add non interactive icon in the buttons section inside the thumbnail preview. To simulate this effect you can use the NonBackground and NonInteractive properties. The first one will remove the border rectangle and mouse hover effects and the second one will disable the button press event.

this.radTaskbarButton1.ThumbnailButtons[0].NoBackground = true;
this.radTaskbarButton1.ThumbnailButtons[0].NonInteractive = true;

Me.RadTaskbarButton1.ThumbnailButtons(0).NoBackground = True
Me.RadTaskbarButton1.ThumbnailButtons(0).NonInteractive = True

Figure 3: NonInteractive Button

WinForms RadTaskbarButton NonInteractive Button

See Also

In this article