Show the overflow of a scrollgroup

It is how these elements work. It's the same with groups that go out of bounds of the artboard.

The overflow of scrollgroups being visible all the time in design mode would probably interfere a lot with other elements, especially if they are above them in the layer hierarchy. For me, personally, that behavior would be more disruptive than helpful.

Being able to switch that behavior on or off might be a nice feature, but it's a bit too specific/niche, considering a lot of other much more basic features are still missing from the program. You can still submit a new feature request on uservoice and perhaps it will be implemented at some point, if enough people feel the same way about it.

Hi, hmmm it sounds like it defeats the purpose of using a scroll group, but if it's for presentation purposes, I'd suggest you to disable the scroll group temporarily or create a clone of the artboard and disable scroll group in the cloned one, I think I'd do that way, happy designing!