Dropdown note that overlays other windows

I'm not sure what this is called - I am a fleeing Evernote user - but the reason I kept using it so long was the icon at the top of your screen that you could click on and a scratch pad would drop down. It was incredibly useful for taking notes from emails and things like that, so I imagine someone has made a plugin for it, but I don't know what words to use to find it in the plugin database. What on earth would you call this, and is this a feature I don't know how to turn on or a plugin that can be installed?

Try the DDDot plugin. It does this and a few other things.