# Control what happens on change

> Hide vs grey out, auto-selecting defaults, and resolving selections that became invalid.

Source: CBX documentation, version 3.x (released). Canonical page: https://docs.configbox.at/docs/admin-guide/rules/control-what-happens-on-change. Last updated 2026-08-02.

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> **Audience:** store admins · **Scope:** the behavior fields that accompany a rule · **Last reviewed:** 2026-07-20

**What this does** — A rule only decides *does this apply right now*. The fields described here
decide what the configurator **does** about it — so choices cascade smoothly instead of leaving
customers with hidden-but-selected or suddenly-invalid answers.

## The settings, and when they matter

All of these sit on the question form (the first also on answers), near the Rule section:

- **What to do while the question is disabled** ("display while disabled") — when the rule is not met: **hide** the question/answer entirely,
  or show it **greyed-out** (visible, not selectable). Grey-out is good merchandising for options
  a customer could unlock with a different choice ("Reinforced frame — available with Steel");
  hiding keeps the configurator short.
- **What to do once the question gets enabled** ("behavior on activation") — when a question *becomes* applicable mid-configuration (a rule
  just started matching): leave it empty, or auto-select its default answer so the configuration
  is never incomplete at that moment.
- **What happens if the current answer becomes impossible** ("behavior on inconsistency") — when the customer's current answer *becomes invalid* (its
  answer-rule stopped matching): deselect it, or replace it with the default/another valid
  answer. This is what prevents impossible combinations from surviving in the cart.
- **What happens when the system changes a selection** ("behavior on changes") — whether such automatic corrections happen silently or the customer is
  **asked to confirm** first. Ask when a correction may surprise ("changing the material resets
  your color"); stay silent for obvious cascades.

![The four behavior fields on the question form, highlighted — they sit in the Rule section](./img/behavior-fields.jpeg)

## A worked example

*Question "Color" is hidden while "Finish" is "Raw" (a hide-if rule). The customer picks Raw
after already choosing a color:*

1. The Color question's rule stops applying → it hides (or greys out, per **Display while
   disabled**).
2. Its existing selection is now inconsistent → per **Behavior on inconsistency** it's
   deselected, so the color's price disappears from the summary.
3. Because **Behavior on changes** is set to confirm, the customer sees a prompt first and can
   back out of switching to Raw instead.

## Good to know

- Defaults are the safety net: give every choice question a sensible **Default** answer so
  auto-activation and auto-replacement always have something valid to fall back on.
- Test the flows on the storefront after wiring rules: click through the paths that toggle your
  rules and watch what appears, disappears and resets. Five minutes of clicking catches nearly
  everything.
- Prices always follow the *actual current selections* — a deselected answer's price leaves the
  summary immediately; there is nothing extra to configure for that.