frame/window border-width and interaction with mouse click in window border

[John Lumby <johnlumby hotmail com>]

I use mouse Button-1-move in a window border to resize it.    I have always found it can be tricky to position the mouse correctly since the border is so narrow  -  often the action of clicking the button moves the mouse outside the border (or sawfish thinks it has) and it has some other effect probably on the adjacent window.

When I saw the new frame-part attribute border-width in 1.7,  I thought this might be the answer,  by widening the border.
I can run something like
sawfish-client -e "(set-frame-part-value 'top-border 'border-width 8)"
and after a while all borders on all windows do appear to resize  (actually bottom and side borders are resized too  -  expected?)
but the "clickable" range of pixels does not appear to have been adjusted.     It still slips off if not on the very edge .

Is there some way of widening the clickable range of any/all window borders in 1.7.1?
If not,  would the developer agree that altering the border-width of the frame class ought to do what I want?    Or am I misunderstanding what this is.
And if you can give me a clue where the relevant code is that assigns position to a mouse click and then decides whdther it was inside a border or not, maybe I can change it.

John Lumby

P.S.    Yes,   I know there are other ways of resizing  -  my default bindings have mouse-2-move in the title bar.
        But that is not as convenient since it e.g. does not allow dragging the bottom edge "down",  only dragging the top/right.