New answers tagged text-editor
Command + Option + [ or Command + Option + ] to navigate between open documents in the single window.
Right click on a .txt file in Finder. Choose "Get Info". Expand "Open with:" and choose your preferred text editor in the drop-down. Push the "Change All..." button below the drop-down and then confirm in the dialog that pops up with "Continue". This works on Yosemite (OS X 10.10).
For plaintext tabs, you don't need to replace the entire TextEdit app to change it. I looked at the source they changed and it provides the simpler answer: Open the Terminal and type defaults write com.apple.TextEdit "TabWidth" '4' Where '4' is the number of spaces a tab should be.
Scribblet is the best so far - it's actually just a modified version of TextEdit so that it allows you to take notes and it stores them in folders like Finder does. http://www.palemaverick.com/scribblet/
The Notes app has this feature. Open a note in it's own window (double-click the title) and then the option is under Window/Float on Top. You can assign a keyboard shortcut to it in system keyboard settings (I use ^+⌘+F)
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