enhancementhelp wanted
説明
Pasteboard Viewer updates the view of the pasteboard in real-time, but sometimes you want to preserve the contents even if the pasteboard is cleared or overwritten. For example, when dragging an image in Chrome and then releasing, Chrome clears the pasteboard, so it will be gone from Pasteboard Viewer too.
I haven't yet decided where the toggle should be and what it should look like. Suggestions welcome.