This is useful in a few situations, but it rapidly becomes tedious if you have to position lots of windows. The best application of place is to create special-purpose geometry managers using its relative constraints. A standard application of place is to adjust the boundary between two adjacent windows. The place command lets you specify the width and height of a window, and the X and Y locations of the window's anchor point. The size and location can be specified in absolute or relative terms.
Relative specifications are more powerful.
Example 22-1 uses place to center a window in its parent. A value of 0.5 specifies the middle. The relative height and width settings are used to base a widget's size on another widget. Example 22-2 completely covers one window with another window. You can make a window slightly larger or smaller than the parent by specifying both parameters.