Canvas editor

How selection works across the GCS, ACS, and LGS canvas editors — one-step selection, additive multi-selection, vertex handle dots, and clearing.

Overview

All three design tools — GCS (Section Analyzer), ACS (Concrete Designer), and LGS (Light Gauge Steel) — share the same canvas editor interaction model for selecting geometry. This page covers how selection works; for pan and zoom, see Canvas navigation.

One-step selection

Clicking a vertex or edge immediately selects it. There is no prior hover or focus step — the item is selected on the first click.

This is consistent across all tools and modes. Whether you are using the Select tool in ACS, picking geometry in GCS, or clicking nodes in LGS, a single click always produces a selection without any intermediate step.

Plain click — single selection

A plain click (no modifier key) selects one item and replaces any previous selection:

Shift-click — additive multi-selection

Hold Shift while clicking to extend the current selection:

• Shift-click a vertex — adds it to the selection without removing existing items.
• Shift-click an edge — adds that edge.

The accumulated selection grows until you click the canvas background (clear) or perform an action that consumes it (such as applying a constraint).

Additive multi-selection is required for constraint authoring in ACS and GCS, where you assemble a combination of vertices and edges before the constraint action bar appears.

Outline stroke weight

Section outlines are drawn at 2 px (pre-zoom). When a vertex or edge on an outline is selected the stroke steps up to 3 px to reinforce the active state. Both weights scale inversely with zoom so the outline reads at a consistent visual thickness regardless of how far in or out you are.

Vertex handle dots

Vertex handles — the small circular dot markers at each outline or polygon vertex — are hidden by default to keep the canvas uncluttered. They are revealed when any of the following is true:

• The mouse is hovering over the outline or polygon.
• A vertex or edge is currently selected (single-selection or multi-selection).

This means once you have clicked to select something, the handles stay visible until you clear the selection, making it easy to Shift-click additional vertices without moving the mouse back over the outline first.

The handles remain in the canvas at opacity zero when hidden. This means you can click or drag a vertex without hovering first — the grab registers immediately, and the dot appears as you move.

Clearing the selection

Click anywhere on the canvas background (empty space, not on a vertex or edge) to clear both single-selection and the accumulated multi-selection set.

Keyboard shortcuts

The tool palette on each canvas surface labels every tool button with its keyboard shortcut. Pressing the key activates that tool immediately — no click required.

Shortcuts fire whenever the keyboard is not captured by a text input, an open dropdown, or a dialog. The Ctrl (⌘ on macOS), Alt, and Meta modifiers are excluded — those belong to undo/redo and browser bindings.

Related pages

• Canvas navigation — pan, zoom, and fit controls.
• Constraint creation — using multi-selection to author geometric constraints in ACS.
• Parametric sketcher — managing constraints, the status chip, and the Constraint List Panel.