Bg-picker: Switch focus to separate bg-picker area fires main bg-picker

[otttooming]

Footer bg-picker areas work as expected. Problem manifests when user toggles main bg, then switches to any of the footer bg-picker areas.

[otttooming]

Behavior is caused when user drags color slider to 0, resulting in bg-picker modal disappearing and not triggering proper modal close. Resulting in said modal reappearing when user toggles another unrelated bg-picker area.
Appears to affect in principle other Voog templates, with disappearing modal when color slider dragged to 0. Modal reappearance is specific to Zürich template