This document explains how to define a widget in Visual Tcl.  If you are
making your own widgets for your install of VTcl, you should put your
files in the 'user' subdirectory.  This will ensure that you don't overwrite
any VTcl widgets and that they will not conflict with later releases of VTcl.

You should be careful when defining widgets that you don't overwrite a
default widget type or class.  For example, don't name your widget button,
because you will overwrite the default Tk button type.  And, don't make a
new button and call its Class 'Button', because again, you will overwrite
the default button class.  Instead, try to use your own names for widgets.

Each widget is defined seperately in its own file with the extension .wgt

The following are the possible options in a widget file:


Name		Name of Widget.  This is also considered to be the "type" of
		widget by vTcl.

Class		<class name>
		Widget class

IsSuperClass	<yes | no>
		This widget is a super class widget.  Super class widgets are
		widgets which are not created themselves, but represent
		sub widgets.  Example: scrollbars, scales.  A scrollbar is
		a widget, but vTcl recognizes two different "types" of
		scrollbars: vertical and horizontal.  So, Scrollbar is the
		super class, and scrollbar_v and scrollbar_h are the sub
		widget types.

SuperClass	<class name>
		The super class of this widget.  This widget is a subwidget.

Lib		<lib name>
		Widget library (core, itcl, tix, etc...)

CreateCmd	<command>
		Command to create the widget (defaults to <Class>)

AddOptions	<option>..<option>..
		Options to <Command> when toolbar button is pressed.

Icon		<icon name>
		Toolbar icon (defaults to icon_<name>.gif)

Balloon		<text>
		Text of the toolbar balloon

DefaultOptions	<option> <value> [<option> <value>]*
		Options to <Command> as the widget is created.

DefaultValues   <option> <option>
                Specifies that the given options will take their default
                value instead of the value given by the option database
                at the time the widget is created

DumpCmd		<proc>
		Proc to dump the widget when saving.
		(defaults to vTcl:dump_widget_top)

DumpChildren	<yes | no>
		Dump the widget's children when saving or pasting (yes or no)

InsertCmd	<proc>
		A command executed when the widget is created.
		(defaults to <name>)

DoubleClickCmd	<proc>
		A command executed if the widget is double-clicked.

TreeLabel	<string | proc>
		The string displayed next to the widget in the widget tree.
		If <string> has an @ as the first character, then string is
		the name of a proc to execute that will return the string
		to display.
		The proc must have one arguments: Widget
		    Widget is the widget to get the label for.

TypeCmd		<proc>
		A proc to return what type a widget is.  This must be specified
		if the widget is a super class.  It tells vTcl how to determine
		which subclass widget it is looking at.
		Example: scrollbar:  horizontal or vertical?

AutoPlace	<yes | no>
		Ignore preference and automatically place the widget.

Resizable	<none | both | horizontal | veritcal>
		How the widget can be resized: none, both, horizontal, vertical

Function	<menu text> <command>
		Adds a widget-specific function to the right-click menu.

NewOption	<option> <text> <type> <choices> <title>
		Adds a new option to the option list.

Export		<proc>
		This proc needs to be exported when a program is saved.
		When creating new widget types that are not standard, it
		is sometimes necesary to create procs to handle certain
		functions of the widget.  By specifying the proc as an
		Export, vTcl will export that proc to the save file when
		it saves, ensuring that the program will still run with
		the necesary procedures.

WidgetProc	<proc>
		This is the proc that widgets of this type will be aliased
		to when Command Aliasing is turned on.

AliasPrefix	<string>
		When auto-aliasing is turned on, widgets are automatically
		assigned an alias name based on AliasPrefix and the order
		of their creation.
		(defaults to <Class>)

ResizeCmd	<proc>
		This is the proc that is called when a widget is grabbed by
		a handle and resized.  vTcl takes care of whether or not
		the widget CAN be resized based on the <Resizable> argument.
		Once vTcl has determined that it can resize this widget, it
		calls this command.
		The proc must have three arguments: Widget Width Height
		    Widget is the widget being resized
		    Width is the new width for the widget
		    Height is the new height for the widget
		(default is vTcl:adjust_widget_size)

AdditionalClasses <class> <class> ...
                Lists classes of children that vTcl should know of (eg.
                Notebook, Tabset, Page, ... for Iwidgets)