It’s like something you used to have to deal with back in the 90s. This feels unnecessarily cumbersome, especially since many effects can be applied within the app’s editing section (those that can’t are greyed out and labelled “(layer only)”).
The interface is divided into two parts: although you can add effects and titles to your project, from simple letters appearing on screen to complex 3D animations, all from within HitFilm Pro, you can’t actually do it all while editing: in order to add some of those effects, you need to turn your clip into a composite shot, which prepares it for all manner of alterations that will be applied to it.
The workspace on display is versatile enough so you can easily change the layout to suit your needs, adding, removing or reordering panels as you see fit.