Scrollbars and LittleArrows

Michael J. Lew michaell at
Mon Sep 6 00:49:18 EDT 2004

At 7:00 PM -0400 5/9/04, Arthur Urban wrote:
>My latest oddity is that my littlearrows never reaches its endValue. If I
>have a control with a startValue of 1 and an endValue of 10, the
>thumbPosition always stops at 9. I was wondering if this was due to the
>thumbSize being 1? But then shouldn't my thumbPositional also stop at 2?

It is a little-known oddity of Rev scrollbars that the real page 
increment is the pageIncrement property value minus the lineIncrement 
property value and the real end value is the endValue property minus 
the thumbsize property. Another thing to keep in mind is that the 
numberFormat property of a slider (sets the number of decimal points 
shown when show value is set to true) affects the lineIncrement 
property value (!) and hence also the page increment (!!).

I have Bugzillarated these issues without any relief: the 
lineIncrement affect on pageIncrement is considered to be a useful 
FEATURE and so my bug has been resolved as not a bug.

I think there is a design flaw here that has cascaded through the 
various forms of the scrollbar object.

You can learn to deal with the oddities by playing with a scrollbar 
with a script like this:
on mouseUp
   put the lineInc of me && the pageInc of me && the thumbsize of me
   put return & the thumbposition of me && the endvalue of me after msg
end mouseUp

Hope that makes the mud less opaque.

Michael J. Lew

Senior Lecturer
Department of Pharmacology
The University of Melbourne
Parkville 3010

Phone +613 8344 8304

New email address: michaell at

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