How to change dropdown backcolor?

[Sydney]

We have several raddropdown controls on a form, and they are set to use Windows 7 theme. 
Some of these need to have a different background color to indicate that they are required. 

We have tried
1.  setting the BackColor property in the Properties window - does not change the color. 
2.  setting it in the code (rddVendor.BackColor=color.yellow)....does not change the color. 

I'm sure we are missing something rather simple....can anyone point us in the right direction? 
Other info....VS 2010, vb.net, framework 4.03xxxx, Telerik Q1 2012 SP1

Thanks.

UPDATE.....using the following lines of code, we can get a fully colored background.....but if there is a way to fully color the background with only one line, that would be preferrable.  Since BackColor is a property of the control, I would expect that to do it....

rddVendor.DropDownListElement.TextBox.BackColor = Color.Yellow
rddVendor.DropDownListElement.TextBox.Fill.BackColor = Color.Yello

[Richard Slade]

Hello Sydney, 

Please see this forum answer that will answer your question. 
Regards, 
Richard

[Stefan]

I am marking Richards post as answer. Please refer to the article mentioned. 

Let us know if you have any other questions.
 
Regards,
Stefan
the Telerik team