Add always on top icon on tool bar, or add shortcuts

[Leroy]

Hello, I have used XnView for many years, and I am very hope to add this. You know, sometimes, I need open image for reference when I painting or do something. always on top is very useful. but currently, it's only in options setting. so an icon or shortcuts would make operate quickly. it's useful. hope to add. sorry my poor English. very thanks for XnView team.