By default, RadFormDecorator does not decorate Textboxes.
For the time being, my suggestion is to not
set the RadFormDecorator DecoratedControls="All",
but set it to "Default"
or some other value that will skip decorating textboxes. Thus you will have the chance to style them yourself to fit the look you need.
In the future we will introduce the ability to style textboxes without rounded corners.
the Telerik team
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