Gtk.TextTag - invisible property vs ScrolledWindow

[Lusito <core roughael net>]

I'm trying to use the Gtk.TextTag "invisible" property, which seems to 
do its job in hiding the text.
But the scrollbars are not updated accordingly, so with little text 
visible there are still scrollbars and with much text, some text can't 
be seen.
This seems to depend on what invisibility setting has been used before 
adding text.

Also, sometimes it seems like empty lines are left where text was 
hidden, even tho all the newlines are inside the hidden text.
This only happens in some rare occasions tho.

What I'm trying to accomplish is a log viewer which colors text 
depending on a category and has an option to hide and show each category.
Of course I could just rebuild the text every time, but it'd be nicer if 
I could use the invisible feature, since then it will stay at the 
previous position (more or less).

Any help is greatly appreciated.