layerling 1.58.0

• Cancelling a sketch returns to the 3D editor: Cancelling a new or an edited sketch (extrude and revolve) left the toolbar on the Sketch tab, now empty, until you clicked 3D editor yourself; finishing one switched back as expected. Cancelling now switches back too and closes the stroke panel. Reported by @prmod3d in #212.
• Every grid line grows with the zoom: Only the centre cross and the plate border grew as you zoomed in; the other grid lines stayed one pixel wide and faded into a light plate, most of all in the Tinkercad look. Every grid line now also lies on the plate as a narrow band - a twentieth of the grid step, twice that for the darker lines - so it grows as you zoom in, as in Tinkercad, while the pixel line keeps the grid visible from afar. Where lines cross, the colour is laid once, so no darker dots form. Reported by @prmod3d in #143.
• A design from a newer layerling says so: A design saved by a newer layerling may hold what an older one does not know - a new shape, a new setting, fonts of one's own. Where that kept it from opening, the reason was a bare technical one such as "unknown shape type"; now it names both versions and says that reloading the page brings the newest one. Where it opens, the notice says it was saved by a newer version and newer things may look different. This helps from this version on; older ones still give the plain reason.
• Fonts of your own for text: Under Font, "Your own fonts …" opens a window that takes a TrueType, OpenType or WOFF file, and in Chrome and Edge on a computer also a font installed there (the browser asks once for permission; Firefox, Safari and phones choose the file instead). The font is read once into the typeface format the built-in fonts use, so curved text, edge treatment and STEP work on it; outlines drawn the PostScript way round are turned, and strokes that overlap - script and variable fonts - are merged into one outline. It is kept in this browser. A design stores only the outlines of the letters its texts use, in every undo state - never the font file - so it opens with its lettering on any computer, and letters typed there without the font come from Sans. WOFF2 and font collections are refused with a reason. The guide explains the browsers and what passing a design on means for a font's licence. The MCP bridge has layerling_add_font and layerling_list_fonts, and font takes a font of one's own by id or name.
• Round gear teeth: Gears have a third tooth shape, Round: each tooth one arc over the tip and each gap one arc over the root, running smoothly into each other, like Tinkercad's Useful gear. Small printed gears with them are more forgiving and turn more easily than involute ones, and on a knob they make a smooth grip. They are set like involute teeth by number of teeth, module and backlash (no pressure angle). They stand lower - tip 0.6 module above the pitch circle, root 0.85 below - so the outside diameter is module × (teeth + 1.2); the tooth is half a pitch thick on the pitch circle less half the backlash, so round gears with the same module mesh at the usual centre distance. The exact body is made of true arcs, for the edge tool and STEP. The MCP bridge takes gearProfile: "round". Suggested by @luk-saw and @prmod3d in #201.
• Round knurling: The knurl has a third pattern, Round: grooves and ridges along the axis as a smooth wave of arcs, the same shape as the round gear teeth, but with the number of grooves, the depth and the end chamfer free - a pleasant grip for a knob. Round grooves stay shallower than 0.45 of the pitch round the grip, or the ridges would bulge at their foot; a greater depth gives way. It is an exact body of true arcs, chamfered ends included. The MCP bridge takes knurlPattern: "round". Suggested by @prmod3d in #201.