Side-bar jumps to clicked location on bar when it should not

[Wise Melon]

Though this is slightly hard to explain, basically when I click a part of the side-bar which is the actual bar I drag down and not the space I drag it through if it is on the right and I click far on the right of the actual bar instead of just doing nothing or allowing me to drag it it behaves as though I have clicked on the area where the bar is not on that area and jumps down to that point. Perhaps a screencast would be better at showing what I mean though so here is one: https://github.com/numixproject/numix-gtk-theme/files/238683/Numix_Side-Bar_Issue.mp4.zip

I originally reported the issue here (https://github.com/numixproject/numix-gtk-theme/issues/399) as I thought it was just a Numix issue, but now that I am running Ubuntu GNOME 16.04 with GNOME 3.20 I have found the issue also present with Adwaita, so either they both just happen to have the same issue, or the bug is more central than that.

[Wise Melon (wise-melon-deactivatedaccount)]

I tried to add an affected package as the numix-gtk-theme one but it just added shimmer-themes, is this the parent package or something or should this be removed as a listed affected package?

[Jeremy Bícha (jbicha)]

I was unable to understand the issue you described.

I don't think this is a theme issue. For it to be a theme issue, it would have to work in some themes but not in others. I believe the scroll bar is handled by GTK 3.