Remove/modify the title bar

[m^2]

The trouble is in hiding title bar??? As far as I know this is just an option for the GUI element or not?

The problem is that Ghisler is very unwilling to do any GUI changes. Few people will request it, so it won't be done.
What Photoshop has is not just hidden titlebar but a custom control that lets you do things like dragging the window. And making one takes much more than an hour that he seems to consider to be max for minor requests, especially with GUI.

You can request it on ghisler.ch, but don't have much hope...