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Practical Programming in Tcl & Tk, Third Edition
By Brent B. Welch

Table of Contents
Chapter 48.  Tcl 7.4/Tk 4.0

Scrollbar Interface

The interface between scrollbars and the scrollable widgets has changed. Happily, the change is transparent to most scripts. If you hook your scrollbars to widgets in the straightforward way, the new interface is compatible. If you use the xview and yview widget commands directly, however, you might need to modify your code. The old interface still works, but there are new features of these operations that give you even better control. You can also query the view state so you do not need to watch the scroll set commands to keep track of what is going on. Finally, scrollable widgets are constrained so that the end of their data remains stuck at the bottom (right) of their display. In most cases, nothing is broken by this change. Chapter 30 describes the scrollbar protocol starting at page 431.

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