Run "xtbl 6 -file tst6" for an example of how to modify a layout at runtime.

Step 1 : Hit "_justify_" and the labels will justify as indicated.
Step 2 : Hit "_gravity_" and the labels will migrate as indicated.
Step 3 : Hit "_fill_" and two labels will expand to fill slack in their rows
         (At this point, the layout will be messed up without the patch...)
Step 4 : Hit "_text_" and the top label will change text, forcing the entire
	 layout to reformat, because the new text is narrower and taller than
	 the original text.

To run other examples, the general usage instructions follow.

Usage: xtbl # -file tst#
    # can be one of the following : 5, 6, 7, 12, 13, 15, 17, 22
    E.g., xtbl 6 -file tst6

or,

Usage: xtbl # -string "description"
    E.g., xtbl 3 -string "tab(;) snl(~);\nc c\nc.\nup~left;up~right\nbottom"

User places the resulting window which contains two "Tbl"s side by side.
The left Tbl is the one given by the file or description string.
The right Tbl is a column of command widgets, which, when activated,
read the file indicated by the label to modify the left Tbl.
See the 4 files for format descriptions.  There are commands/files for
text, justification, gravity, and fill mode.

    E.g., if _text_ contains:
	
	2
	0
	abc
	1
	xyz

    The first two Label widgets will have their text changed
    to "abc" and "xyz".


