Given that the current state of the UI is in a massive mess as of now, a lot of backend simplification needs to be done to remove boilerplate inflation, particularly regarding modular context menus (e.g. entity_actions, entity_keyframes, entity_variables, group_actions, and brush_actions). All of these context menus should be folded into BrowserUI as an available setup with custom navigation menu styling (either image icons, square icons, or regular context menu styling).
Additionally, CSS technical debt should be removed (see Backend Planning), and the whole UI made to be more in-line with raster image editors such as Paint.NET and grand-strategy games. These applications have minimal UI learning curves and so are great to base the standard editor off of. A central modal prompt should also be brought in with the capacity for maximisation/minimisation for fullscreen editing. It would have an alternative version in which panels can be directly overlaid on top of the screen.
Additionally, SFX could enhance the overall feel of the editor.
The backend /actions/ folder needs to be split up per action type, similar to T&T2 by rough Class type. CSS stylesheets can also be refactored by taking the current CSS in load order, and dumping them into a single file to see what could be simplified. Additionally, entity-ui-wysiwyg files need to be moved over and integrated into UF's context menu.
There should be onrightclick dynamic context menus. These would be appended with position: absolute; to a general on right click dynamic context menu layout. It would then make sense to port config context menus (i.e. entity keyframes, group actions) to said dynamic context menus.
This system would be added as a part of BrowserUI. Onrightclick dynamic context menus could be set to a specific anchor element and be nested, making them ideal for adding rapid UI options/dropdown context menus, i.e. right clicking on a chevron to set ‘minimise by default’.
Many of these onrightclick context menus would be in settings state, and state namespaces could be defined for their inputs to belong to.
Left Sidebar.
The general layout of the Left Sidebar needs to be changed such that Entity UI shrinks the general page container vertically, instead of being horizontally minimised which can lead to layout confusion. Moving the Date selector to the top right instead, as happens in Paradox games, will make greater sense.
Topbar.
The topbar as it currently is needs to have a fixed rem restricted height and to have a higher z-index to fix its positioning on smaller monitor sizes. It otherwise appears to suit its purpose.
Right Sidebar.
Group/Entity Selection.
Group/Entity Selection should be refined to make multi-select generally feasible. This would work by being bound to left click when the brush is disabled, whilst right click opens up the Entity UI menu instead in addition to selecting it.
Any further context menus should ideally be bound to cursor position.