Azoth: FastStatusButton semantics, fixed setting custom state.
Monocle: DocumentTab::RegenPageVisibility().
Monocle: PageGraphicsItem::Map{From,To}Doc().
Monocle: PagesLayoutManager::GetPages().
Monocle: pages visibility in document coords.
Monocle: notify on scheduled relayout.
Monocle: visible area indication in ThumbsWidget.