#98 Sync/F9 from All Windows (not just main window)

[Mike Clements]

I use NixNote on Linux XFCE with multiple desktops. I often have notes open in separate windows on different desktops. But Nixnote can sync only from the main window. If the Sync/F9 key worked from all windows, I could just hit F9 from any Nixnote window -- instead of navigating through desktops to find the main window.
This is probably simple & easy to implement, and a BIG productivity boost.