# Ruby/Tk: how to get Scrollbar to stay scrolled on non-scroll widget?

**URL:** <https://www.ruby-forum.com/t/ruby-tk-how-to-get-scrollbar-to-stay-scrolled-on-non-scroll-widget/161530>\
**Category:** Ruby\
**Created:** [February 27, 2009, 4:46am UTC](https://www.ruby-forum.com/t/ruby-tk-how-to-get-scrollbar-to-stay-scrolled-on-non-scroll-widget/161530 "2009-02-27T04:46:10Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![chris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/958977/32.png) [@chris](https://www.ruby-forum.com/u/chris)\
**Post date:** [February 27, 2009, 4:46am UTC](https://www.ruby-forum.com/t/ruby-tk-how-to-get-scrollbar-to-stay-scrolled-on-non-scroll-widget/161530/1 "2009-02-27T04:46:10Z")

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Hello all,

I am trying to get a new grid control working (similar to a TreeView  
without the tree) and my most recent problem is to get the Scrollbar  
to respond to the changes it initiates in the grid. I’ve tried a few  
things, but nothing on the web seems to deal with getting a Scrollbar  
to work with anything that isn’t already inside Tk and has the correct  
hooks. The closest I’ve come is some allusions at

> **[TkDocs Tutorial](https://tkdocs.com/tutorial/onepage.html)**
>
> Modern Tk Tutorial for Python, Tcl, Ruby, and Perl

The code I was trying includes this just after the widgets are setup:  
@v\_scroll.command proc{|\*args| self.yview(\*args)}

# self.yscrollcommand proc{|\*args| @v\_scroll.set(\*args)}

self.yscrollcommand proc{|\*args| @v\_scroll.set  
(@y\_scroll\_start\_fraction, @y\_scroll\_end\_fraction)}  
The scrollbar responds since I defined yview to send to internal  
yviewMoveTo and yviewScroll methods (as I found somewhere else): the  
move commands are sent to the correct methods. However once the user  
releases the scrollbar it always returns to the original position.

I tried defining it the same as in existing widgets, eg:  
def yscrollcommand block  
configure\_cmd ‘yscrollcommand’, block  
self  
end  
But even if I include TkConfigMethod and TkComm in the class, it can’t  
figure out what TkConfigMethod’s path is (and I certainly don’t  
know). I also tried some other things like using the standard \*args  
version above and have this definition of yscrollcommand:  
block.call(@y\_scroll\_start\_fraction, @y\_scroll\_end\_fraction)  
But apparently I am missing some deeper understanding of what the  
process is here.

Has anyone been successful at this, or otherwise knows what kind of  
abstraction histrionics are required?

Thanks!

-Chris

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<div class="post-metadata">

**Author:** ![chris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/958977/32.png) [@chris](https://www.ruby-forum.com/u/chris)\
**Post date:** [February 27, 2009, 7:16am UTC](https://www.ruby-forum.com/t/ruby-tk-how-to-get-scrollbar-to-stay-scrolled-on-non-scroll-widget/161530/2 "2009-02-27T07:16:02Z")

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Sorry for replying to myself, but I just stumbled on a possible  
solution: using the typical  
@v\_scroll.set(@first\_viz,@last\_viz)  
at the end of the yview() declaration. In my few trials it seems to  
work even though it doesn’t fit in the prescribed callback mechanism  
that every book and website describes. Which, incidentally, is why I  
didn’t think of it sooner.

Does this add a problem that will bite me later?