How do you keep a window in all spaces?

Some apps have this as an internal feature, but is there any way to keep a specific window visible no matter which space you're in?


Solution 1:

I figured out how to keep an entire application on any screen.

  1. Right click the application in the dock
  2. Mouse-ver Options
  3. Select All Desktops from the Assign to sub-menu.

But what if I just want, say one spreadsheet in excel to follow me to any desktop, while it keeps the rest where they are?