fix(combobox): open panel on chevron click (x-combobox + x-multi-combobox)

[markaddleman]

Problem

Clicking the dropdown arrow (chevron) on x-multi-combobox (and x-combobox) is a no-op. Users expect it to open the panel, just like clicking the input area does.

Fixes #267.

Root cause

The chevron already has a pointerdown listener wired up that toggles the panel:

(defn- on-chevron-pointerdown [^js el ^js evt]
  (.preventDefault evt)
  (if (du/has-attr? el model/attr-open)
    (close-panel! el ...)
    (do (open-panel! el ...) ...)))

…but the chevron's CSS set pointer-events:none, so the chevron was never the target of a pointerdown — pointer events passed straight through it and the handler was dead code. The pointer fell through to the wrapper, which has no handler, so nothing happened. Clicking "to the left" worked only because that region is the actual <input>, whose native focus event opens the panel.

Fix

Remove pointer-events:none from the [part=chevron] rule in both components, and add cursor:pointer for affordance. The handler, preventDefault, and open/close toggle were already correct — they just needed the chevron to be hit-testable.

Scope

I audited every chevron/arrow/trigger-bearing component. These two are the only ones affected: in both, the chevron carries its own click handler while the rest of the control is a text input (no parent button to catch a fall-through click). Everywhere else (x-dropdown, x-date-picker, x-select, x-popover, x-tooltip, …) the chevron either sits inside a <button>/native <select> that handles the click, or pointer-events:none is on a decorative arrow triangle or a disabled state — all correct.

Tests

Added two regression tests per component:

• chevron-is-hit-testable-test — asserts the chevron's computed pointer-events is not "none". This is the test that actually guards the bug: a synthetic dispatchEvent bypasses CSS hit-testing, so only the computed style catches it.
• chevron-pointerdown-toggles-open-test — documents the handler contract (open on first pointerdown, close on second).

Full suite: 5100 tests pass headless (npm test); clj-kondo clean.

🤖 Generated with Claude Code

[avanelsas]

@markaddleman thanks for finding and fixing this! Approved and merged