DialogsCssFile Property

The DialogCssProperty property is useful in scenarios when a custom skin is used or you just want to import your own CSS file to customize the appearance of the iframe-based dialogs. It allows you to include your custom skin CSS in the editor dialogs. Follow the steps to see how you can set it:

1. Place the editor's Skins folder within your web application - the Skins folder can be found in the controls' installation folder of the Telerik® UI for ASP.NET AJAX suite.

2. Set the EnableEmbeddedSkins property to false.

ASP.NET

<telerik:RadEditor RenderMode="Lightweight"
   runat="server" ID="RadEditor1"
   Skin="Default"
   EnableEmbeddedSkins="false"
   DialogsCssFile="~/Skin/DialogCSS.css">
</telerik:RadEditor>

3. Choose the desired skin and set the editor's Skin property to point to it e.g. Skin = "Default"

4. Add manually to the page's head the following CSS files:

ASP.NET

<link href="Skins/<CurrentSkin>/Window.<CurrentSkin>.css" rel="stylesheet" type="text/css" /> 
<link href="Skins/<CurrentSkin>/Editor.<CurrentSkin>.css" rel="stylesheet" type="text/css" /> 

5. Create new CSS file e.g. DialogCSS.css and put in it references to the following CSS files which will style the different Telerik controls in the editor dialogs:

CSS

@import url("Ajax.<CurrentSkin>.css");
@import url("ColorPicker.<CurrentSkin>.css");
@import url("FormDecorator.<CurrentSkin>.css");
@import url("Grid.<CurrentSkin>.css");
@import url("Input.<CurrentSkin>.css");
@import url("PanelBar.<CurrentSkin>.css");
@import url("Rotator.<CurrentSkin>.css");
@import url("Slider.<CurrentSkin>.css");
@import url("Splitter.<CurrentSkin>.css");
@import url("TabStrip.<CurrentSkin>.css");
@import url("ToolBar.<CurrentSkin>.css");
@import url("TreeView.<CurrentSkin>.css");
@import url("Upload.<CurrentSkin>.css");
@import url("Widgets.<CurrentSkin>.css");
@import url("Window.<CurrentSkin>.css");
@import url("ComboBox.<CurrentSkin>.css");
@import url("Button.<CurrentSkin>.css");
@import url("Editor.<CurrentSkin>.css");
@import url("ListBox.<CurrentSkin>.css");

6. Set the editor's DialogsCssFileproperty to point to the DialogCSS.css e.g. DialogsCssFile="~/Skins/Default/DialogCSS.css"

For more information check the following article: Registering an external skin of RadEditor.