Grid Line Tool behaviour

[Mitchell (the other one)]

I'm not sure if this is part of the new Grid Line Tool behaviour or not.  First attached image - I have created a sheet with two layers, Main Floor Plan and Building Grid.  Second image, I have doubled clicked to enter Edit Viewport, then choose Annotations expecting to add a note below the drawing title.  When I click on the grid lines / bubble their settings (shoulder, bubble scale etc.)  can be edited as an annotation.  As a possible feature, I'm trying to think of how this helps with workflow.  

[Mitchell (the other one)]

And in answer to my question, a little reading of the online manual and while gridlines should be placed on a design layer, they can be edited (to a degree) through Viewport Annotation.