feat(ui): Select Other — pick what lies under something else (#503)

Hold the left button still (long-press on touch) or right-click › Select Other… to list everything under the cursor: sketch points and curves ("Line 3", "Point (arc 2 centre)"), vertices, edges, faces, bodies, profiles, planes and axes, filtered like a click and by the open dialog's active input. Hovering a row lights it up; clicking selects it (Shift/Ctrl add) or feeds the dialog. A repeat click on the same spot with nothing changed selects the next thing there; a double-click keeps its own actions.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/book/src/guide/shortcuts.md

@@ -26,4 +26,13 @@ Keys handled by the window itself:
 | F6 | fit the view to the model |
 | Esc | cancel the running command, or clear the selection |
 
+Mouse and touch:
+
+| Action | Result |
+|---|---|
+| Click | select (Shift or Ctrl adds) |
+| Click again on the same spot | select the next thing under the cursor (click cycling) |
+| Hold the left button still (long-press on touch), or right-click › Select Other… | list everything under the cursor to pick from |
+| Double-click a sketch curve or edge | select its chain or tangent loop |
+
 Help › Keyboard Shortcuts in the app lists the current bindings, including any you changed.

docs/book/src/guide/ui-tour.md

@@ -14,7 +14,14 @@
   origin, bodies, sketches, construction planes, canvases, joints and components. The eye shows or
   hides an item, a component's radio button makes it the active component, and right-clicking any
   row gives that item's menu. Rows drag into groups and other components.
-- **Viewport.** Click to select, Shift or Ctrl to add, drag for a window or crossing box. The
+- **Viewport.** Click to select, Shift or Ctrl to add, drag for a window or crossing box. To
+  reach something under something else (two lines drawn on top of each other, coincident points,
+  an edge in front of a face, overlapping bodies), hold the left button still for half a second
+  (long-press on a touch screen) or right-click › **Select Other…**: a list of everything under
+  the cursor opens there, the sketch being edited first. Hovering a row lights it up; clicking it
+  selects it (Shift or Ctrl adds), and in a command's dialog it goes to the active selection box.
+  Esc or a click elsewhere closes the list. Clicking again on the same spot, with nothing changed
+  in between, selects the next thing in that list. The
   wheel zooms at the cursor, the middle button pans and right-drag orbits freely (the mouse
 <  preset in Preferences switches to SolidWorks, Inventor, Alias or Tinkercad style). On a
   trackpad, pinch zooms and two-finger scroll pans (Navigation › Two-finger scroll pans;

docs/control-protocol.md

@@ -56,6 +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.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 |