Go all-in on HUDs for field layout designers’ element libraries

[brandonkelly]

Description

Removes the always-visible element library from field layout designers, in favor of an “Add” button within each tab which opens the element library in an HUD.

CleanShot.2025-01-02.at.08.39.18.mp4

Why?

• Less scrolling! There’s now more horizontal space for an additional tab column within the FLD workspace, and on larger field layouts, the library is always going to be fully vertically aligned with the current viewport.
• Quicker element selections. We can now support click/Return-based selection for adding an element to the tab the HUD is opened for, rather than exclusively requiring drag-n-drop. And newly-created fields are now immediately added to the tab.
• Consistent UI regardless of container size. Previously we were using a similar UI (except with disclosure menus) for smaller containers, via Make the FLD responsive #14411.

Related issues

• Usability issues with drag & drop on Field Layout Designer #1076
• 3.5 Field Layout Designer: collapsing tabs #8885
• Adding the new field through entry type page - add newly added field to the top of the list #15080