I agree with the intent here - tabs are fine, but should only be used at the start of a line, but basically, it is hopeless :-(
All lines should match this regex: ^[\t]*[^\t\r\n]*$
If the editor can do this reliably, then tabs aren't really needed.
(Really, if *all* editors that are used on a given code base can do this).
To get it right, the editor needs to know exactly how many tabs are needed at the start of the line -- so it must know the indent level.
If it knows this much, then no leading tabs are needed at all - the editor can just display the text indented correctly (virtual beautify).
If the intention of actually putting in the correct number of leading tabs is to allow for editors that aren't aware of this convention, then OK - but now you are back to the same old problems with mixing tabs and spaces, relying on people to get it right and not doing it a little different to suit their whim.
See the comment by Alan Kilborn in the first link.
Alan doesn't get it, but that is basically the problem.