In the overview dialog it's not possible to point on some point of the image, just panning is allowed.
Yes, that's right. That hasn't been implemented, so it's a feature request, not a bug.
Do you mean the Overview Docker? If so, this patch may have already added this feature: https://phabricator.kde.org/D12178 It's been pushed, so it should be coming in the next release, I think.