There are all these attributes that can be used to decorate properties and classes so that the Property Grid control knows to handle them. One of these attributes is PersistenceModeAttribute, which specifies how to persist the information in ASP.Net markup. More often than not, you need to persist a complex object with subproperties as an inner tag. In that case one uses [PersistenceMode(PersistenceMode.InnerProperty)]. For the possible values of the constructor parameter, just follow the link if interested.
The problem comes when you want to persist the properties as attributes, in the ASP.Net specific "flattened" syntax, using a hyphen to separate property from subproperty. (<Style Color="red"/> as an inner tag is the same as Style-Color="red" as an attribute). You want this because some controls interpret their inner content as controls to be placed in them, such as the Panel control. You cannot add a Style tag in it because it just gets rendered in the page. The solution is to not use PersistenceMode! Of course, you might say, that's obvious. But it is not when your property already has the PersistenceModeAttribute decorating it and you are desperately looking for a parameter that does what you want. There is no such parameter. Not decorating the property is a separate option and it is the default behavior.