Practical Programming in Tcl & Tk, Third Edition

Choosing the Parent for Packing

In nearly all of the examples in this chapter, a widget is packed into its parent frame. In general, it is possible to pack a widget into any descendent of its parent. For example, the .a.b widget could be packed into .a, .a.c or .a.d.e.f. The -in packing option lets you specify an alternate packing parent. One motivation for this is that the frames introduced to get the arrangement right can cause cluttered names for important widgets. In Example 23-4 on page 335, the buttons have names like .one.alpha and .one.right.delta, which is not consistent. Here is an alternate implementation of the same example that simplifies the button names and gives the same result:

Example 23-18 Packing into other relatives.

# Create ...