A better user experience when a Firefox extension loads a new tab custom page
N.B. This workaround is for macOS, using Keyboard Maestro. I have not tried equivalents elsewhere. On Windows, AutoHotkey can bind a hotkey, send Ctrl+T, select and clear the address bar, then Escape. On Linux, AutoKey is the usual analogue; under Wayland you may need something like ydotool. The Firefox new-tab focus behaviour itself is not macOS-specific.
In the previous post I described Slinky, a self-hosted start page, and mentioned that I use the New Tab Override extension so Firefox opens it on every new tab. That works, but the default behaviour is a little ugly.

PCB fabricators require a board outline on the `Edge.Cuts` layer to specify the board size and shape. While drawing the board outline in the PCB editor is straightforward and uses the standard line and shape drawing tools, it is convenient to retain standardized board outlines and related parts, such as fasteners, as reusable footprints. During the board layout process, you can simply plop a board outline, along with perfectly-placed mounting holes into the editor and you can concentrate on placing components and routing. Also, having a standard library of board outlines gives you a predictable set of size choices for enclosures and for ordering SMD stencils.