The 1.4 update was a milestone for power users, introducing several "pro" features: Release Notes - SideNotes - Apptorium
SideNotes is designed as a digital "post-it note wall" that lives on the edge of your Mac's screen. It allows you to capture ideas without switching away from your current application. SideNotes 1.4.6
Full support for markdown formatting, including headers, code blocks, lists, and task checkboxes. menu bar icon
Notes are organized into folders with customizable colors and themes. or global keyboard shortcut.
Notes slide in from the screen edge via a hot side, menu bar icon, or global keyboard shortcut.