Arduino IDE: setting tab indent to another value

Change default tab setting to four (4) spaces in IDE (applies to version 1.6.10 and later.)

Steps:

1. Exit Arduino IDE. (otherwise the closing of application will overwrite preferences file.)

2. Edit preferences.txt on two lines:

editor.tabs.expand=true

editor.tabs.size=4

Save and exit.

3. Create new file:

   • formatter.conf

   in your Arduino directory (in the same location as preferences.txt)

   • in windows: 
     C:\Program Files (x86)\Arduino\lib = C:\Users\{USRNAME}\AppData\Local\Arduino15

   • on mac: it's /Users/{USRNAME}/Library/Arduino15/

     Add this one line:

     indent=spaces=4
     

Then save and relaunch.

 Tabbing and auto-formatting (^t) will indent consistently.



References:

Information source: (https://github.com/arduino/Arduino/issues/5012)