fix(ui): Select Other keeps its list readable on dense meshes (#636)

Select Other keeps at most 20 rows per kind, nearest first, so a dense spot (a modelled thread, an imported mesh) no longer lists thousands of rows. The title shows how many were under the cursor in all, and ui.selectOther reports it as total.

docs/control-protocol.md

@@ -56,7 +56,7 @@ unit regardless of the design, pass an expression with one: `"value": "50 mm"` o
 | `ui.drag` | `x0`, `y0`, `x1`, `y1`, `button?`, `shift?`, `ctrl?`, `steps?`, `hold?`, `hold_end?` | press, move, release; a left drag on the model is a box selection (left to right: window, right to left: crossing); with OpenSCAD navigation, plain left-drag on empty space orbits, Shift+left-drag box-selects, and drags starting on sketch geometry edit it; `hold` keeps the button down that many frames first (a right press-and-hold opens the marking menu, releasing over a direction picks it), `hold_end` that many frames at the end (a sketch drag shows its snap) |
 | `ui.menu` | `x?`, `y?`, `target?`, `close?` | with a point: open a context menu there as a right-click would (the viewport's marking menu, or a browser menu with `target: {"type": "body", "name"} \| {"type": "sketch", "id"} \| {"type": "component", "id"}`); without: the open menu (`radial` and `items`: id, label, shortcut, enabled) |
 | `ui.menuPick` | `item`: id or label | runs an item of the open menu, as clicking it does |
-| `ui.selectOther` | `x?`, `y?`, `pick?`, `add?`, `hover?`, `close?` | Select Other: with a point, list everything pickable there (as holding the left button does); `pick`: select row `pick` (`add`: as Shift-click; with a dialog open, into its active input); `hover`: light a row up; without: the open list (`open`, `at`, `rows`: label, icon, sel) |
+| `ui.selectOther` | `x?`, `y?`, `pick?`, `add?`, `hover?`, `close?` | Select Other: with a point, list everything pickable there (as holding the left button does); `pick`: select row `pick` (`add`: as Shift-click; with a dialog open, into its active input); `hover`: light a row up; without: the open list (`open`, `at`, `total`: everything under the cursor, `rows`: label, icon, sel, at most 20 per kind, nearest first) |
 | `ui.rename` | `text?`, `commit?` (default true) | finishes the rename box a Rename item opened |
 | `ui.selection` | | the selection, the open dialog's inputs, the hovered item, and the active sketch's drawn dimensions (`dimensions`: id and text centre, `dimension_selected`, `dimension_editing`) |
 | `ui.worldToScreen` | `points`: `[[x, y, z]…]` world points | their screen points |