Should property sets values overwrite values in the system settings

Should property set values overwrite values that are set up the system settings?

Reason i'm asking is if i change any values on the default property set for TinyMCE that are also present in the System Setting for the tinymce namespace they don't seem to have any effect.

For example, the "skin". Doesn't matter what i set it to within the property set i can't override it. Other settings work that can't be set within the system setting.

I've tried in a few version of revo including current latest 2.2.0 pl2.

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