setting default values for strings

In my skin edits, I created a means of the user to change some basic colors.   That works just fine.  My issue is for a fresh setup of the skin, the string values for the colors are null.

For example, from settings.xml in the userdata
<setting id="PlayerTextColor" type="string"></setting>

The side effect of this is that the text has no color (and thus not visible).   The same situation exists for textures, but they all default to the basic color of the texture (in this case white).

In some other skins I've seen stuff like this in variables.xml but it does not seem to help.

    <variable name="PlayerTextColor">
        <value condition="String.IsEmpty(Skin.String(PlayerTextColor))" />
        <value>white</value>
    </variable>

I've poked at this for a couple days, and can't seem to get past this.   Any help is appreciated.