The placer allows the direct specification of (absolute/relative) widget coordinates and sizes. It does not really make a geometry handling, and leaves the responsibility for the layout to the user. Here is a small example of a layout, created with the placer. First, the code to place the widgets:
place .s1 -x 0 -y 50 -relwidth .1 -relheight .7
place .l1 -relx .1 -y 50 -relwidth .9 -relheight .7
place .b1 -relx .5 -y 30 -width 60 -height 40 -anchor c
The resulting layout (as shown in figure ) has a button at the top, named .b with a fixed
width (60 pixel) and height (40 pixel), a fixed y position
(30 pixel) and a relative x position of 50 percent of the
parent's width. So the button has always the specified size,
is always 30 pixel away from the top border, and always
centered in the middle of the parent. The scrollbar and the
listbox use 70 percent of the parents height and (together)
the complete width of the parent. They are placed below the
button.