Set default value for Draw Shape and Draw Text.

       private void radButton1_Click(object sender, EventArgs e)
        {
            ShapeInfo info = new ShapeInfo(ShapeType.Square, Color.Red, Color.Yellow,3);
            this.radImageEditor1.ImageEditorElement.StartDrawing(info);
        }

        private void radButton2_Click(object sender, EventArgs e)
        {
            this.radImageEditor1.ImageEditorElement.DrawString(
                "Text to draw",
                18, //font size
                Color.Yellow, //Text color
                100, //horizontal position
                50, //vertical position
                45);
        }

        public class CustomImageEditorDialogFactory : ImageEditorDialogFactory
        {
            public override ImageEditorBaseDialog CreateDialog(Type type, RadImageEditorElement imageEditorElement)
            {
                ImageEditorBaseDialog dialog = base.CreateDialog(type, imageEditorElement);
                if (dialog is DrawShapeDialog)
                {
                    ((RadColorBox)dialog.Controls[0].Controls["radColorBoxBorder"]).Value= Color.Red;
                }
                return dialog;
            }
        }