AudioPreferencesPanel does not dynamically change its layout

[pixelzoom]

By default, the Audio Preferences for Number Play looks like this. It's a really strange layout, but that's not the probem I'm reporting.

If we run Number Play with screens=3,4, then "Hear Total" toggle is irrelevant, and it's hidden by setting its visible: false. The layout then looks like this, which is really wrong. The left column is empty, so the right column should have moved to the center.

The relevant code is in AudioPreferencesPanel.ts. excludeInvisibleChildrenFromBounds: false is probably the culprit here - it's default is true for FlowBox/VBox/HBox. But note the comment.

    // Some contents of this Dialog will be dynamically removed. Dont resize when this happens because we don't want
    // to shift contents of the entire Preferences dialog.
    const contentOptions: VBoxOptions = {
      align: 'left',
      spacing: PreferencesDialog.CONTENT_SPACING,
      excludeInvisibleChildrenFromBounds: false
    };

[marlitas]

The culprit for this was the contentNode being created in PreferencesPanelSection. I addressed this in the above commit and made sure there were no reverberations to other sims, most notably I checked: John Travoltage, Ratio and Proportion, and Quadrilateral.

@pixelzoom can you review and close if all looks good? I'm mostly curious if I used combineOptions appropriately here.

Also if any collateral effects are seen by other devs from this change in other sims please re-open and ping me.

[pixelzoom]

Verified that layout looks as expected with and without screens=3,4 for NumberPlay.

Use of combineOptions looks fine.

Closing.