I really like that the tabs are on top. Looks super nice! I'd noticed, though, that the dividing lines seem somewhat unorganized or flush together. I made a mock-up of what it currently is, and what I might suggest adjusting it to. Reproducible: Always Suggestion made while using Kdenlive 16.07.70 master git build from ppa:kdenlive/kdenlive-master. Kubuntu 16.04 x64, plasma desktop 5.6.4
Created attachment 99136 [details] Tabs as they currently are.
Created attachment 99137 [details] Proposed edited tabs.
Created attachment 111347 [details] Screenshot example of partial progress in latest Kdenlive 18.08 beta0 appimage build UPDATE: Looks like this has been partially fixed in latest builds. Both "Effects" and "Transitions" tabs now look a lot smoother.
Thanks for your report Jesse, the interface has improved over the last versions. Also some of this can also be related to the style and theme.