I have modified editor.tabs.size=4 in ...AppData\Local\Arduino15\preferences.txt (Windows 7) and restarted the IDE.
Hit tab and the cursor jumps 4 spaces and after typing the new line, hitting return aligns the next line correctly - either directly underneath or indented another 4 spaces.
CTRL-T changes all the spacing back to 2 characters!
Do I have to change another preference somewhere? I had no joy getting this work in previous IDE's either.
Thanks in advance.