Perl in a Nutshell, 2nd Edition

The pack Geometry Manager

With the pack geometry manager, widgets cannot overlap or cover each other, either partially or completely. Once a widget is packed into a window, the next widget is packed in the remaining space around it. pack sets up an “allocation rectangle” for each widget, determined by the dimensions of the parent window and the positioning of the widgets already packed into it. This means that the order in which you pack your widgets is very important.

By default, pack places widgets at the top center of the allocation rectangle. However, you can use options to pack to control where a widget is placed and how much padding is placed around it. Options for pack are:

-side => side

Puts the widget against the specified side of the window. Values for side are left, right, top, and bottom. The default is top.

-fill => direction

Causes the widget to fill the allocation rectangle in the specified direction. Values for direction are none, x, y, and both. The default is none.

-expand => boolean

Causes the allocation rectangle to fill the remaining space available in the window. Values are yes, no, 1, and 0. The default is 0 (no).

-anchor => position

Anchors the widget inside the allocation rectangle. Values for positionare n, ne, e, se, s, sw, w, nw, and center. The default is center.

-after => $ widget

Puts the widget after another widget in packing order.

-before => $ widget

Puts the widget before another widget in packing order.

-in => $ window

Packs the widget inside another window ...