#2918 ttk::notebook slider not correct

[Joerg Honerla]

In ttk::notebook the last slider wasn't correctly displayed. In 8.5.9 it runs perfect.

The behavior can be seen at:
8.5.9 http://www.ets.uni-due.de/~honerla/tcl/8.5.png
8.6.b2 http://www.ets.uni-due.de/~honerla/tcl/8.6.png

System Linux/Xorg x86_64
Tcl/Tk 8.6.b2 build from source code
Tcl/Tk 8.5.9 from distribution DVD (Opensuse 11.4)