1. Select the ColorBox's ellipses to open the Color Dialog

on load of its Color Dialog the Web & System tabs have selected colors by default

2. Select the Web tab

In the below for Web its Transparent

3. Select "OK"

the colour doesn't get updated in the ColorBox on Color Dialog close

Which is understandable as a colour change hasn't occurred only the tab has been changed

However, following the same scenario above.

If the user wanted to select Transparent, they would need to:

2. Select a different colour even though its selected on load by default

3. Select back on Transparent

4. Select OK in order to see the colour reflected in the ColorBox

This is not ideal for an end user.

Is there a way to have no selection by default in the Web & System tabs?

Add a RadColorBox on the form and use the following code: 

            this.radColorBox1.Value = Color.Black;
            RadColorSelector selector = this.radColorBox1.ColorDialog.ColorDialogForm.RadColorSelector as RadColorSelector;
            selector.OldColor = Color.Green;

Workaround:

            this.radColorBox1.ColorDialog.ColorDialogForm.SelectedColor = Color.Green;
            this.radColorBox1.Value = Color.Black;