# Using custom themes

Since version R1 2010, Visual Style Builder we have introduced a new theming mechanism, which allows you to create or modify one theme at a time, but for all RadControls simultaneously. The following part shows how you can save and use the custom theme in your application.

## Saving a custom theme

When you choose the **Save** option, the Visual Style Builder automatically detects whether a theme has been opened and edited. If yes, it simply overwrites the already loaded files with the new XML data. However, if you created a new theme without loading files, the Visual Style Builder will display the **Save As** dialog and will ask you to choose location and theme name for the newly created theme. What is important is to set the **ThemeName** and to check **Save As Package**, which will save the theme as .tssp file.

> caption Figure 1: Save the custom theme.

![themes-using-custom-themes](https://www.telerik.com/products/winforms/documentation/assets/a3f6f9bc2ca97ae98430ba09a7f69065/themes-using-custom-themes.png)

## Loading theme package

The **ThemeResolutionService** class exposes two static methods that allow you to load a theme package:

* **LoadPackageResource:** This method loads a theme package file that is contained in the project as an [EmbeddedResource](http://msdn.microsoft.com/en-us/library/0c6xyb66\(VS.80\).aspx). This is the preferable method for loading a theme package since the resource path to the package is not changed when the application is deployed. The path construction is *DefaultProjectNamespace.ThemeFolder.ThemePackageFile*. The *ThemeFolder* part should only be used if the package is contained in a folder under the main project directory and if the project programming language is C#. In VB.NET project you do not need to include *ThemeFolder* part even if the package file is contained in a folder.

#### Loading package resource

 

 

```C#
ThemeResolutionService.LoadPackageResource("SamplesCS.CustomTheme.tssp");

```

```VB.NET
ThemeResolutionService.LoadPackageResource("SamplesVB.CustomTheme.tssp")

```

 

* **LoadPackageFile:** This method loads a file from a specified directory on the system. Depending on how the directory is defined (full or relative), the path to the package may change when the application is deployed on another machine.

#### Loading package file

 

 

```C#
ThemeResolutionService.LoadPackageFile(@"C:\CustomTheme.tssp");

```

```VB.NET
ThemeResolutionService.LoadPackageFile("C:\CustomTheme.tssp")

```

 

> important Our **TelerikHelper** class has a static method that determines whether a theme is dark: TelerikHelper.**IsDarkTheme**(themeName). This method is used when an editor in grid activates (if theme is not dark, a white back color is applied to the editor) and the ribbon bars (RichTextEditor, Spreadsheet, Diagram), where different icons set is applied if the theme is dark. So, if you saved a custom theme with a name different from our predefined dark themes, this method, TelerikHelper.**IsDarkTheme**(themeName) will consider the theme as light. This is why in **R2 2020** we introduced a way to register a dark theme and to act as a dark theme everywhere: ThemeResolutionService.**RegisterDarkTheme**(string themeName).

## Applying a theme to an entire application

 

 

```C#
ThemeResolutionService.ApplicationThemeName = "CustomTheme";

```

```VB.NET
ThemeResolutionService.ApplicationThemeName = "CustomTheme"

```

 

## Applying a theme to single control

 

 

```C#
radButton1.ThemeName = "CustomTheme";

```

```VB.NET
radButton1.ThemeName = "CustomTheme"

```

 

## Applying a theme to all instances of a specific control in a form

 

 

```C#
foreach (Control control in this.Controls)
{
    RadButton button = control as RadButton;
    if (button != null)
    {
        button.ThemeName = "CustomTheme";
    }
}

```

```VB.NET
For Each button As RadButton In Me.Controls
    If button IsNot Nothing Then
        button.ThemeName = "CustomTheme"
    End If
Next

```

 

## See Also

* [Saving and Loading Theme Files](https://www.telerik.com/products/winforms/documentation/tools/visual-style-builder/working-with-visual-style-builder/saving-and-loading-theme-files)

* [How to Customize a Theme](https://www.telerik.com/products/winforms/documentation/knowledge-base/customize-a-theme)

* [How to Modify Themes Programmatically](https://www.telerik.com/products/winforms/documentation/knowledge-base/modify-themes-programmatically)