Add custom user toggles for watchface

Hi there,

I've been working on a minimalistic WatchFace for the Garmin Venu (and soon other devices) and would like to set a custom toggle for the WatchFace. I am not talking about settings this that come in the os of the Garmin watch:

```
(settings.xml)
    <setting propertyKey="@Properties.UseMilitaryFormat" title="@Strings.MilitaryFormatTitle">
        <settingConfig type="boolean" />

    </setting>

(properties.xml)

    <property id="UseMilitaryFormat" type="boolean">false</property>

```

I want to create a custom toggle for the watchFace itself. So for instance:

```

(settings.xml)

    <setting propertyKey="@Properties.MyCustomProp" title="@Strings.MyCustomPropTitle">

        <settingConfig type="boolean" />

    </setting>

(properties.xml)

    <property id="MyCustomProp" type="boolean">false</property>

```

A user should be able to modify this from the "Select WatchFace Screen" (just like the Garmin default ones do on the Garmin Venu, where they provide a pen icon below the WatchFace, see screenshot).

 

Is there any documentation on how to implement this? Or is this something that is restricted to Garmin's own WatchFaces (since I cannot recall any custom WatchFace with these settings).

Thanks,

Coen