From: Albert Wagner <alwagner@...>
Date: 2002-08-27T03:52:36+09:00
Subject: Tk scrollbar with elided text

I am using a TkText as a base for an editor, with folding implemented by using 
TkTags with the 'elide' option.  However, the vertical scrollbar behaviour is 
not what I expected.  The slider within the scroller changes size depending 
on whether elided text is or is not within the window. 
 For example:
I have several blocks of text, each block consisting of a header line that is 
always visible and any number of body lines tagged so that they may be elided 
as a group. 

If no bodies are elided, then the scrollbar works as expected.

If all bodies are elided, then the scrollbar moves slowly as if it is actually 
scrolling the elided lines and the slider changes size depending on whether a 
small number or large number of elided lines are within the window.

If there is a mix of blocks, with some bodies elided and some not, then the 
slider changes both size and speed depending on whether the bodies within the 
window or elided or not.

I know that this must sound confusing.  But perhaps some Tk user has 
encountered this before.  Here is my definition:
  
		#-------------------------------------
		# Define Vertical Scrollbar
		@vbar = TkScrollbar.new(parent,
			'orient'  => 'vertical',
			'command' => proc{|*args|@doc.yview(*args)}
			).grid(
			'in'		=> @bigGrid,
			'padx'      => 1,
			'pady'      => 1,
			'row'       => 0,
			'col'       => 2,
			'rowspan'   => 1,
			'columnspan'=> 1,
			'sticky'    => 'news'
			)

		# synchronize @doc and @lineDoc to use same scrollbar
		@doc.yscrollcommand(proc{|first, last|
			@vbar.set(first, last)
			@lineDoc.yview('moveto', first)}
			)
# @doc is the main TkText and @lineDoc is a slave TkText containing line 
numbers.