ttk::panedwindow possible enhancements

Dear Tk experts,
please allow me to ask for opinions on the ttk::panedwindow widget.
IMHO it may get some love.
My main challenges:
1) in vista theme, the Sash is invisible. There is just a 3 pixel width line which changes the cursor, if the mouse hoovers over it.
Users may easily overlook it, specially, if the sash is at position 0 or adjacent to another sash.
2) if there is a resize by sash drop, I want to get a callback to save the sash position for later restoring.
3) if there is a sash drag, I want to control the valid values. For example, always make a part of the window visible (like a tablelist title row).
4) I would love to attach additional functionality to the sash, like right click->menu or double-left-click->zoom.
I suppose, 2-4 may be solved by exposing the widget name of the sash.
For point 1, I hope magic Csaba may look into it.
There are partly solutions on the wiki page, which bind for point 2 and 3 on Button 1 down on the widget. For me, this is more a work-around than a solution.
Thanks for all !
Harald