Where a String holds a state, and an editor is provided to edit the state.
return the editor for the string
return the string represented by the GUI state
some clients of this code may provide a context for the string, so for example a preview could be created or units detected or null to clear the context. This method can be ignored, and the code should assume a context will be provided. This is typically the object containing the property.
set the current string value, representing a state.