Formatting Rules - Continuation indent using Tab Characters - results in spaces?

Hi there, i've imported some formatting rules from a eclipse-formatting file.

Now, somehow the IDE formats at some point with spaces rather than expected tabs.
I did not find the approriate setting, in order to change the behaviour.

Is it a bug, or is there a setting i don't see?

See screenshot:



Thanks and Greetings.

I'd expect really tabs rather than spaces.