The control bars are now the ONLY visible controls; the node input widgets
they drive are hidden via a new hideWidgets() util (uiComponents.js). The
widgets keep existing -- values still serialize into the workflow and flow to
Python as inputs -- they just stop rendering on the node body.
- Multi / VTK preview / Batch: `mode` widget hidden (bar Mode selector drives
it). Batch keeps its `index` widget visible (useful for typing an exact
index).
- Dual: `layout`, `mode`, `opacity_1`, `opacity_2` all hidden. Opacity moves
into the bar (shown only for the Overlay layout) and is applied
CLIENT-SIDE: changing it updates the hidden widgets (persistence + next
run) and re-posts to the viewer immediately -- no re-run. render() now
prefers widget values over the last message's, which also fixes the
`|| 1.0` bug that made opacity 0 impossible.
No Python or export-format changes, per direction.
PozzettiAndrea
54c3ad01aa