TL;DR
Display radar coverage preview when placing a blueprint that contains a radar.What ?
Placing a single radar (ghost or not) shows a blue preview of its coverage on the minimap (top right) - it is useful if you want perfect coverage without overlaps - but when you place a blueprint containing a radar this preview is not shown.Basically it was already reported as a bug but it was explained it is not a bug but a limitation in order to optimize performance, even if I don't think radar is an item that is usually present in multiple copies in a blueprint.
In OT it's also suggested to adopt the same approach used for turret range blueprinting, with an explicit option for toggling it.
I hope it's acceptable to repost the request here, in the suggestions section, in order to avoid it being lost in the "not a bug" section.