We have a function that sets the thickness of the outline for the parcels on our map. They are merely outlines of the surveyed property boundaries. We want to make the "subject" property outlined a little bolder so it stands out from the surrounding properties. The way it works now is we have an ISimpleLineSymbol object, and set the width to 5. This works great when we first fire up ArcMap (10.4.1) unless we close out the map and create one that encompasses a wider area, then go back to the smaller map. Somehow on the second try, the line is so heavy it looks like it was scrawled with a crayon, and even overwrites the text symbols inside. It looks like the width property is in "points". Does it depend upon the IMapFrame.MapScale or is it proportional to something else?