Best lanuage or framework for creation of a gui?

I'd start with a .NET language: .NET (in one form or another) is now available for Windows, Web, Linux, Android, iOS, ...

I'd suggest start with C# / WinForms where it's easy to create a scrollbar in code (though it's even easier to create one in the designer):

VScrollBar sb = new VScrollBar();
sb.Dock = DockStyle.Right;
Controls.Add(sb);
sb.Scroll += Sb_Scroll;

The four lines are all you need:
1) Create a vertical scroll bar instance.
2) Set it to "hug" the right hand side of the container (Form, Panel, UserControl, whatever)
3) Add the scrollbar to the container
4) Add a handler so that you can do something when it scrolls.

All you have to do now, is decide what the scroll bar should do and write code in teh handler method.

And most of the time, you don't have to do that: containers "know" when they need a scrollbar and add it themselves so you don't have to!