I would like to edit existing Theme for our whole application - i read documentation page http://www.telerik.com/help/winforms/themes_workingmodifyingexisting.html and I wonder whether it's possible to "edit whole existing Office2007Black" theme - not just certain controls and then merge it into our .xml theme file.
4 Answers, 1 is accepted

You can't modify the 'whole Office2007Black theme' (or another theme for different controls). You can modify Office2007Black theme for each control separately and then merge the themes in one big xml file.
As to the RadForm, its theme is a combination of two themes - the first one is for the RadTitleBar and the second one is for the client part of the form. Currently, opening Visual Style Builder from RadForm design-time is not supported. However, I am attaching the Office2007Black theme for the titlebar part and the client part to my message. Feel free to modify them according to your preferences.
I hope this helps. If you have additional questions, feel free to contact me.
Greetings,
Nikolay
the Telerik team
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Hello Darren Breed,
Thank you for your interest in the Desert theme. I am attaching the titlebar and client parts of the RadForm to my message. Feel free to modify them according to your design preferences.
Please note that have a known issue with modifying an existing RadFrom theme in Q2 2009 SP1. This issue will be addressed in Q3 2009. For the time being, please follow the instructions below:
1. Open the Form's Desert Theme XML file and find the following XML construct:
<
StylesheetRelations
>
<
RadStylesheetRelation
ControlType
=
"Telerik.WinControls.UI.RadForm"
ElementType
=
"Telerik.WinControls.RootRadElement"
/>
</
StylesheetRelations
>
This is normally positioned at the end of the file.
2. Change the stylesheet relation as shown below:
<
StylesheetRelations
>
<
RadStylesheetRelation
ControlType
=
"Telerik.WinControls.UI.RadForm"
ElementType
=
"Telerik.WinControls.UI.FormRootElement"
/>
</
StylesheetRelations
>
3. Save the file and open it in the Visual Style Builder. You will see the settings of the Desert theme applied to the Form, i.e. the outer thin border will be set to dark brown, the inner thicker border will be set to lighter brown and the background color of the Form will be set to white.
4. Change the elements' appearance according to your preferences and save the file.
5. Open the saved file in a text editor and again find the following construct:
<
StylesheetRelations
>
<
RadStylesheetRelation
ControlType
=
"Telerik.WinControls.UI.RadForm"
ElementType
=
"Telerik.WinControls.UI.FormRootElement"
/>
</
StylesheetRelations
>
6. Change it accordingly and save the file:
<
StylesheetRelations
>
<
RadStylesheetRelation
ControlType
=
"Telerik.WinControls.UI.RadForm"
ElementType
=
"Telerik.WinControls.RootRadElement"
/>
</
StylesheetRelations
>
You should be able to use the modified theme in your project by loading it from the RadThemeManager component or by building a Theme Component and referencing it in your project.
I hope this helps. If you have additional questions, feel free to contact me.
Best wishes,
the Telerik team
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