Applying tag to empty space in GtkTextBuffer

[Dmitry Koval <koval donapex net>]

I'm doing some kind of WYSIWYG editor and using GtkTextEditor as a base
framework.

The problem I have faced is applying some tag to an empty space.
For instance user has pushed an indent button while the GtkTextBuffer is
empty. At this point I have a single iterator and appropriately I can't
apply any tag. But the cursor should be moved further by an indentation
space.
I could change the properties of the whole widget, but it will affect
everything, not the single line I should change.

First what comes to mind is putting some invisible char and applying tag
around it, but it looks more like a workaround, not as a native
solution.

Any pointers?

-- 
Dmitry Koval <koval donapex net>