Question about vertical delimiter and tabs

[XPEHOPE3KA]

Look at the screenshot:
http://net.atspace.us/total1.PNG

At the top: a TC instance with clear ini and with disabled command line and the buttons (it doesn't influence at all - just to let you see). At the bottom there is "normal" TC instance. Look at the vertical delimiter. At the upper TC instance it is some pixels thinner. At Russian forum it was discovered that such an effect is due to TABS (there are NO tabs at the top, and there are tabs at the bottom).

So the questions are:
Why so?
Is it difficult to make (=implement) the delimiter look thin even with tabs?

[ghisler(Author)]

What you see here is actually the border of the tab control. I don't think that there is a way to hide it, sorry.