The Tab size setting only applies to the current file and any subsequently opened files. Changing the tab spacing
for one file does not automatically change it for all the other files that are already open. The tab setting you
choose is stored with the MRU list, so if you re-open a file from the MRU, the old setting comes back (for that file
Note that the new value you apply to the tab setting becomes the default for any file opened or created after that
point (apart from those in the MRU list). So if you change the tab setting to, say, 3, the setting for the current
file changes, but not that of any other open file. Any new file that you create or load from that point, however, will
be created with a default tab spacing of 3.