Thank you for writing.
Actually, RadToolStrip does not support adding a background image. However, you can manually extend the default behavior by adding an ImagePrimitive to its elements. Please consider the following code snippet:
ImagePrimitive imagePrimitive =
imagePrimitive.Image = global::Test_RadToolStrip.Properties.Resources.my_background_image;
You have to keep in mind that there is a limitation on this implementation: RadToolStrip's layout does not allow for stretching the image in the added ImagePrimitive element.
Let me know if you have any additional questions.
the Telerik team
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