How to specify custom background for DXEditors

In our themes, the Control.BackgroundProperty is defined by several elements with different colors, gradients, margins, paddings and corner rounding. You can't specify this complex functionality with only the Control.BackgroundProperty property. You can implement your own template using the TextEditThemeKey key ({dxet:TextEditThemeKey ResourceKey=BorderTemplate}). Also, you need to bind to the Background property.