#  Copyright (c) 1991-1994 The Regents of the University of California.
#  Copyright (c) 1994-1996 Sun Microsystems, Inc.
#  See the file "license.terms" for information on usage and redistribution
#  of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
#

=head1 NAME

Tk::Wm - Communicate with window manager

=for category Tk Geometry Management

=head1 SYNOPSIS

S<    >I<$toplevel>-E<gt>I<method>(?I<args>?)

=head1 DESCRIPTION

The B<wm> methods are used to interact with window managers in
order to control such things as the title for a window, its geometry,
or the increments in terms of which it may be resized.
The B<wm> methods can take any of a number of different forms, depending on
the particular I<method> argument.
All of the forms expect I<$toplevel>, which must be a
top-level window object.

The legal forms for the B<wm> methods are:

=over 4

=item I<$toplevel>-E<gt>B<aspect>(?I<minNumer minDenom maxNumer maxDenom>?)

If I<minNumer>, I<minDenom>, I<maxNumer>, and I<maxDenom>
are all specified, then they will be passed to the window manager
and the window manager should use them to enforce a range of
acceptable aspect ratios for I<$toplevel>.  The aspect ratio of
I<$toplevel> (width/length) will be constrained to lie
between I<minNumer>/I<minDenom> and I<maxNumer>/I<maxDenom>.
If I<minNumer> etc. are all specified as empty strings, then
any existing aspect ratio restrictions are removed.
If I<minNumer> etc. are specified, then the method returns an
empty string.  Otherwise, it returns
a array containing four elements, which are the current values
of I<minNumer>, I<minDenom>, I<maxNumer>, and I<maxDenom>
(if no aspect restrictions are in effect, then an empty string is
returned).

=item I<$widget>-E<gt>B<attributes>( I<?args?> );

This subcommand returns or  sets  platform  specific  attributes
associated with a window.

=over 4

=item I<$widget>-E<gt>B<attributes>;

Returns a list of the  platform specific  flags  and  their  values. 

=item I<$widget>-E<gt>B<attributes>( I<?option?> );

Returns  the  value for the specific option.

=item I<$widget>-E<gt>B<attributes>( I<?option value option value...?> );

Sets one or more of the values. The values are as follows:

On Windows, B<-disabled> gets or sets whether the window is in  a 
disabled state. B<-toolwindow> gets or sets the style of the window 
to toolwindow (as defined in the MSDN). B<-topmost> gets or sets 
whether this is a topmost window (displays above all other windows).

On Macintosh, there are currently no special attribute values.

On Unix, there are currently no special attribute values.        

=back

=item I<$toplevel>-E<gt>B<client>(?I<name>?)

If I<name> is specified, this method stores I<name> (which
should be the name of
the host on which the application is executing) in I<$toplevel>'s
B<WM_CLIENT_MACHINE> property for use by the window manager or
session manager.
The method returns an empty string in this case.
If I<name> isn't specified, the method returns the last name
set in a B<client> method for I<$toplevel>.
If I<name> is specified as an empty string, the method deletes the
B<WM_CLIENT_MACHINE> property from I<$toplevel>.

=item I<$toplevel>-E<gt>B<colormapwindows>(?I<windowList>?)

This method is used to manipulate the B<WM_COLORMAP_WINDOWS>
property, which provides information to the window managers about
windows that have private colormaps.
If I<windowList> isn't specified, the method returns a list
whose elements are the names of the windows in the B<WM_COLORMAP_WINDOWS>
property.
If I<windowList> is specified, it consists of a list of widgets;
the method overwrites the B<WM_COLORMAP_WINDOWS>
property with the given windows and returns an empty string.
The B<WM_COLORMAP_WINDOWS> property should normally contain a
list of the internal windows within I<$toplevel> whose colormaps differ
from their parents.
The order of the windows in the property indicates a priority order:
the window manager will attempt to install as many colormaps as possible
from the head of this list when I<$widget> gets the colormap focus.
If I<$widget> is not included among the windows in I<windowList>,
Tk implicitly adds it at the end of the B<WM_COLORMAP_WINDOWS>
property, so that its colormap is lowest in priority.
If I<$widget>-E<gt>colormapwindows is not invoked, Tk will automatically set
the property for each top-level window to all the internal windows
whose colormaps differ from their parents, followed by the top-level
itself;  the order of the internal windows is undefined.
See the ICCCM documentation for more information on the
B<WM_COLORMAP_WINDOWS> property.

=item I<$toplevel>-E<gt>B<command>(?I<value>?)

If I<value> is specified, this method stores I<value> in I<$toplevel>'s
B<WM_COMMAND> property for use by the window manager or
session manager and returns an empty string.
I<Value> must have proper list structure;  the elements should
contain the words of the command used to invoke the application.
If I<value> isn't specified then the method returns the last value
set in a B<command> method for I<$toplevel>.
If I<value> is specified as an empty string, the method
deletes the B<WM_COMMAND> property from I<$toplevel>.

=item I<$toplevel>-E<gt>B<deiconify>

Arrange for I<$toplevel> to be displayed in normal (non-iconified) form.
This is done by mapping the window.  If the window has never been
mapped then this method will not map the window, but it will ensure
that when the window is first mapped it will be displayed
in de-iconified form.  Returns an empty string.

=item I<$toplevel>-E<gt>B<focusmodel>(?B<active>|B<passive>?)

If B<active> or B<passive> is supplied as an optional argument
to the method, then it specifies the focus model for I<$toplevel>.
In this case the method returns an empty string.  If no additional
argument is supplied, then the method returns the current focus
model for I<$toplevel>.
An B<active> focus model means that I<$toplevel> will claim the
input focus for itself or its descendants, even at times when
the focus is currently in some other application.  B<Passive> means that
I<$toplevel> will never claim the focus for itself:  the window manager
should give the focus to I<$toplevel> at appropriate times.  However,
once the focus has been given to I<$toplevel> or one of its descendants,
the application may re-assign the focus among I<$toplevel>'s descendants.
The focus model defaults to B<passive>, and Tk's B<focus> method
assumes a passive model of focusing.

=item I<$toplevel>-E<gt>B<frame>

If I<$widget> has been reparented by the window manager into a
decorative frame, the method returns the platform specific window
identifier for the outermost frame that contains I<$toplevel> (the
window whose parent is the root or virtual root).  If I<$toplevel>
hasn't been reparented by the window manager then the method returns
the platform specific window identifier for I<$toplevel>.

=item I<$toplevel>-E<gt>B<geometry>(?I<newGeometry>?)

If I<newGeometry> is specified, then the geometry of I<$toplevel>
is changed and an empty string is returned.  Otherwise the current
geometry for I<$toplevel> is returned (this is the most recent
geometry specified either by manual resizing or
in a B<geometry> method).  I<NewGeometry> has
the form B<=>I<width>B<x>I<height>B<+->I<x>B<+->I<y>, where
any of B<=>, I<width>B<x>I<height>, or B<+->I<x>B<+->I<y>
may be omitted.  I<Width> and I<height> are positive integers
specifying the desired dimensions of I<$toplevel>.  If I<$toplevel>
is gridded (see L<"GRIDDED GEOMETRY MANAGEMENT"> below) then the dimensions
are specified in grid units;  otherwise they are specified in pixel
units.  I<X> and I<y> specify the desired location of
I<$toplevel> on the screen, in pixels.
If I<x> is preceded by B<+>, it specifies
the number of pixels between the left edge of the screen and the left
edge of I<$toplevel>'s border;  if preceded by B<-> then
I<x> specifies the number of pixels
between the right edge of the screen and the right edge of I<$toplevel>'s
border.  If I<y> is preceded by B<+> then it specifies the
number of pixels between the top of the screen and the top
of I<$toplevel>'s border;  if I<y> is preceded by B<-> then
it specifies the number of pixels between the bottom of I<$toplevel>'s
border and the bottom of the screen.
If I<newGeometry> is specified as an empty string then any
existing user-specified geometry for I<$toplevel> is cancelled, and
the window will revert to the size requested internally by its
widgets.

=item I<$toplevel>-E<gt>B<wmGrid>(?I<baseWidth,baseHeight,widthInc,heightInc>?)

This method indicates that I<$toplevel> is to be managed as a
gridded window.
It also specifies the relationship between grid units and pixel units.
I<BaseWidth> and I<baseHeight> specify the number of grid
units corresponding to the pixel dimensions requested internally
by I<$toplevel> using B<Tk_GeometryRequest>.  I<WidthInc>
and I<heightInc> specify the number of pixels in each horizontal
and vertical grid unit.
These four values determine a range of acceptable sizes for
I<$toplevel>, corresponding to grid-based widths and heights
that are non-negative integers.
Tk will pass this information to the window manager;  during
manual resizing, the window manager will restrict the window's size
to one of these acceptable sizes.
Furthermore, during manual resizing the window manager will display
the window's current size in terms of grid units rather than pixels.
If I<baseWidth> etc. are all specified as empty strings, then
I<$toplevel> will no longer be managed as a gridded window.  If
I<baseWidth> etc. are specified then the return value is an
empty string.
Otherwise the return value is a array containing
four elements corresponding to the current I<baseWidth>,
I<baseHeight>, I<widthInc>, and I<heightInc>;  if
I<$toplevel> is not currently gridded, then an empty string
is returned.
Note: this command should not be needed very often, since the
B<Tk_SetGrid> library procedure and the B<-setgrid> option
provide easier access to the same functionality.

=item I<$toplevel>-E<gt>B<group>(?I<$widget>?)

If I<$widget> is specified, it is the the leader of
a group of related windows.  The window manager may use this information,
for example, to unmap all of the windows in a group when the group's
leader is iconified.  I<$widget> may be specified as an empty string to
remove I<$toplevel> from any group association.  If I<$widget> is
specified then the method returns an empty string;  otherwise it
returns the I<$toplevel>'s current group leader, or an empty
string if I<$toplevel> isn't part of any group.

=item I<$toplevel>-E<gt>B<iconbitmap>(?I<bitmap>?)

If I<bitmap> is specified, then it names a bitmap in the standard
forms accepted by Tk (see the B<Tk_GetBitmap> documentation for details).
This I<black and white> bitmap is passed to the window manager to be displayed
in I<$toplevel>'s icon, and the method returns an empty string.  If
an empty string is specified for I<bitmap>, then any current icon
bitmap or image is cancelled for I<$toplevel>.
If I<bitmap> is specified then the method returns an empty string.
Otherwise it returns the name of
the current icon bitmap associated with I<$toplevel>, or an empty
string if I<$toplevel> has no icon bitmap.

=item I<$toplevel>-E<gt>B<iconify>

Arrange for I<$toplevel> to be iconified.  It I<$toplevel> hasn't
yet been mapped for the first time, this method will arrange for
it to appear in the iconified state when it is eventually mapped.

=item I<$toplevel>-E<gt>B<iconimage>(?I<image>?)

If I<image> is specified, then it names a normal Tk image.
This image is rendered into a private I<coloured> bitmap which is passed to
the window manager to be displayed in I<$toplevel>'s icon, and the method returns
an empty string. If an empty string is specified for I<image>, then any current
icon bitmap or image is cancelled for I<$toplevel>.
If I<image> is specified then the method returns an empty string.
Otherwise it returns the name of
the current icon image associated with I<$toplevel>, or an empty
string if I<$toplevel> has no icon image.
The private pixmap is not pre-cleared so images which are partly "transparent"
display rubbish in their transparent parts.

The sizes of images that can be used as icons in this manner are platform
dependent. On Win32 this sets the "large" icon, which should be 32x32, it
will automatically be scaled down to 16x16 for use as a small icon.

=item I<$toplevel>-E<gt>B<iconmask>(?I<bitmap>?)

If I<bitmap> is specified, then it names a bitmap in the standard
forms accepted by Tk (see the B<Tk_GetBitmap> documentation for details).
This bitmap is passed to the window manager to be used as a mask
in conjunction with the B<iconbitmap> option:  where the mask
has zeroes no icon will be displayed;  where it has ones, the bits
from the icon bitmap will be displayed.  If
an empty string is specified for I<bitmap> then any current icon
mask is cancelled for I<$toplevel> (this is equivalent to specifying
a bitmap of all ones).  If I<bitmap> is specified
then the method returns an empty string.  Otherwise it
returns the name of the current icon mask associated with
I<$toplevel>, or an empty string if no mask is in effect.

=item I<$toplevel>-E<gt>B<iconname>(?I<newName>?)

If I<newName> is specified, then it is passed to the window
manager;  the window manager should display I<newName> inside
the icon associated with I<$toplevel>.  In this case an empty
string is returned as result.  If I<newName> isn't specified
then the method returns the current icon name for I<$toplevel>,
or an empty string if no icon name has been specified (in this
case the window manager will normally display the window's title,
as specified with the B<title> method).

=item I<$toplevel>-E<gt>B<iconphoto>(?-default? I<image1> ?I<image2>
...?)

Sets the titlebar icon for  window  based  on  the  named  photo
images.  If -default is specified, this is applied to all future
created toplevels as well.  The data in the images is taken as a
snapshot  at  the  time  of invocation.  If the images are later
changed, this is not reflected to the titlebar icons.   Multiple
images  are  accepted to allow different images sizes (eg, 16x16
and 32x32) to be provided.  The window manager  may  scale  pro-
vided icons to an appropriate size.

On Windows, the images are packed into a Windows icon structure.
This will override an ico specified to wm iconbitmap,  and  vice
versa. [NOTE: This is not implemented yet!]

On  X, the images are arranged into the _NET_WM_ICON X property,
which most modern window managers support.  A wm iconbitmap  may
exist  simultaneously.  It is recommended to use not more than 2
icons, placing the larger icon first.

On Macintosh, this is currently does nothing.

=item I<$toplevel>-E<gt>B<iconposition>(?I<x y>?)

If I<x> and I<y> are specified, they are passed to the window
manager as a hint about where to position the icon for I<$toplevel>.
In this case an empty string is returned.  If I<x> and I<y> are
specified as empty strings then any existing icon position hint is cancelled.
If neither I<x> nor I<y> is specified, then the method returns
a array containing two values, which are the current icon position
hints (if no hints are in effect then an empty string is returned).

=item I<$toplevel>-E<gt>B<iconwindow>(?I<$widget>?)

If I<$widget> is specified, it is a window to
use as icon for I<$toplevel>: when I<$toplevel> is iconified then
I<$widget> will be mapped to serve as icon, and when I<$toplevel>
is de-iconified then I<$widget> will be unmapped again.  If
I<$widget> is specified as an empty string then any existing
icon window association for I<$toplevel> will be cancelled.  If
the I<$widget> argument is specified then an empty string is
returned.  Otherwise the method returns the
current icon window for I<$toplevel>, or an empty string if there
is no icon window currently specified for I<$toplevel>.
Button press events are disabled for I<$toplevel> as long as it is
an icon window;  this is needed in order to allow window managers
to ``own'' those events.
Note: not all window managers support the notion of an icon window.

=item I<$toplevel>-E<gt>B<maxsize>(?I<width,height>?)

If I<width> and I<height> are specified, they give
the maximum permissible dimensions for I<$toplevel>.
For gridded windows the dimensions are specified in
grid units;  otherwise they are specified in pixel units.
The window manager will restrict the window's dimensions to be
less than or equal to I<width> and I<height>.
If I<width> and I<height> are
specified, then the method returns an empty string.  Otherwise
it returns a array with two elements, which are the
maximum width and height currently in effect.
The maximum size defaults to the size of the screen.
If resizing has been disabled with the B<resizable> method,
then this method has no effect.
See the sections on geometry management below for more information.

=item I<$toplevel>-E<gt>B<minsize>(?I<width,height>?)

If I<width> and I<height> are specified, they give the
minimum permissible dimensions for I<$toplevel>.
For gridded windows the dimensions are specified in
grid units;  otherwise they are specified in pixel units.
The window manager will restrict the window's dimensions to be
greater than or equal to I<width> and I<height>.
If I<width> and I<height> are
specified, then the method returns an empty string.  Otherwise
it returns a array with two elements, which are the
minimum width and height currently in effect.
The minimum size defaults to one pixel in each dimension.
If resizing has been disabled with the B<resizable> method,
then this method has no effect.
See the sections on geometry management below for more information.

=item I<$toplevel>-E<gt>B<overrideredirect(?>I<boolean>?)

If I<boolean> is specified, it must have a proper boolean form and
the override-redirect flag for I<$toplevel> is set to that value.
If I<boolean> is not specified then B<1> or B<0> is
returned to indicate whether or not the override-redirect flag
is currently set for I<$toplevel>.
Setting the override-redirect flag for a window causes
it to be ignored by the window manager;  among other things, this means
that the window will not be reparented from the root window into a
decorative frame and the user will not be able to manipulate the
window using the normal window manager mechanisms.

=item I<$toplevel>-E<gt>B<positionfrom>(?I<who>?)

If I<who> is specified, it must be either B<program> or
B<user>, or an abbreviation of one of these two.  It indicates
whether I<$toplevel>'s current position was requested by the
program or by the user.  Many window managers ignore program-requested
initial positions and ask the user to manually position the window;  if
B<user> is specified then the window manager should position the
window at the given place without asking the user for assistance.
If I<who> is specified as an empty string, then the current position
source is cancelled.
If I<who> is specified, then the method returns an empty string.
Otherwise it returns B<user> or $widget to indicate the
source of the window's current position, or an empty string if
no source has been specified yet.  Most window managers interpret
``no source'' as equivalent to B<program>.
Tk will automatically set the position source to B<user>
when a B<geometry> method is invoked, unless the source has
been set explicitly to B<program>.

=item I<$toplevel>-E<gt>B<protocol>(?I<name>?,?I<callback>?)

This method is used to manage window manager protocols such as
B<WM_DELETE_WINDOW>.
I<Name> is the name of an atom corresponding to a window manager
protocol, such as B<WM_DELETE_WINDOW> or B<WM_SAVE_YOURSELF>
or B<WM_TAKE_FOCUS>.
If both I<name> and I<callback> are specified, then I<callback>
is associated with the protocol specified by I<name>.
I<Name> will be added to I<$toplevel>'s B<WM_PROTOCOLS>
property to tell the window manager that the application has a
protocol handler for I<name>, and I<callback> will
be invoked in the future whenever the window manager sends a
message to the client for that protocol.
In this case the method returns an empty string.
If I<name> is specified but I<callback> isn't, then the current
callback for I<name> is returned, or an empty string if there
is no handler defined for I<name>.
If I<callback> is specified as an empty string then the current
handler for I<name> is deleted and it is removed from the
B<WM_PROTOCOLS> property on I<$toplevel>;  an empty string is
returned.
Lastly, if neither I<name> nor I<callback> is specified, the
method returns a list of all the protocols for which handlers
are currently defined for I<$toplevel>.

=over 8

Tk always defines a protocol handler for B<WM_DELETE_WINDOW>, even if
you haven't asked for one with B<protocol>.
If a B<WM_DELETE_WINDOW> message arrives when you haven't defined
a handler, then Tk handles the message by destroying the window for
which it was received.

=back

=item I<$toplevel>-E<gt>B<resizable>(?I<width,height>?)

This method controls whether or not the user may interactively
resize a top-level window.  If I<width> and I<height> are
specified, they are boolean values that determine whether the
width and height of I<$toplevel> may be modified by the user.
In this case the method returns an empty string.
If I<width> and I<height> are omitted then the method
returns a list with two 0/1 elements that indicate whether the
width and height of I<$toplevel> are currently resizable.
By default, windows are resizable in both dimensions.
If resizing is disabled, then the window's size will be the size
from the most recent interactive resize or B<geometry>
method.  If there has been no such operation then
the window's natural size will be used.

=item I<$toplevel>-E<gt>B<sizefrom>(?I<who>?)

If I<who> is specified, it must be either B<program> or
B<user>, or an abbreviation of one of these two.  It indicates
whether I<$toplevel>'s current size was requested by the
program or by the user.  Some window managers ignore program-requested
sizes and ask the user to manually size the window;  if
B<user> is specified then the window manager should give the
window its specified size without asking the user for assistance.
If I<who> is specified as an empty string, then the current size
source is cancelled.
If I<who> is specified, then the method returns an empty string.
Otherwise it returns B<user> or $widget to indicate the
source of the window's current size, or an empty string if
no source has been specified yet.  Most window managers interpret
``no source'' as equivalent to B<program>.

=item I<$toplevel>-E<gt>B<stackorder>( I<?isabove|isbelow $toplevel?> );

The stackorder command returns a list  of  toplevel  windows  in
stacking  order,  from lowest to highest. When a single toplevel
window is passed, the returned list recursively includes all  of
the  window's  children that are toplevels. Only those toplevels
that are currently mapped  to  the  screen  are  returned.   The
stackorder command can also be used to determine if one toplevel
is positioned above or below a second toplevel.  When two window
arguments  separated  by either isabove or isbelow are passed, a
boolean result indicates whether or not the first window is
currently above or below the second window in the stacking order.


=item I<$toplevel>-E<gt>B<state>(?I<newstate>?)

If I<newstate> is specified, the window will be set to
the new state, otherwise it returns the current state of
I<$toplevel>: either B<normal>, B<iconic>, B<withdrawn>, B<icon>, or
(Windows only) B<zoomed>. The
difference between B<iconic> and B<icon> is that B<iconic> refers to a
window that has been iconified (e.g., with the B<iconify> method)
while B<icon> refers to a window whose only purpose is to serve as the
icon for some other window (via the B<iconwindow> method). The
B<icon> state cannot be set.


=item I<$toplevel>-E<gt>B<title>(?I<string>?)

If I<string> is specified, then it will be passed to the window
manager for use as the title for I<$toplevel> (the window manager
should display this string in I<$toplevel>'s title bar).  In this
case the method returns an empty string.  If I<string> isn't
specified then the method returns the current title for the
I<$toplevel>.  The title for a window defaults to its name.

=item I<$toplevel>-E<gt>B<transient>(?I<master>?)

If I<master> is specified, then the window manager is informed
that I<$toplevel> is a transient window (e.g. pull-down menu) working
on behalf of I<master> (where I<master> is
a top-level window).  Some window managers will use
this information to manage I<$toplevel> specially.  If I<master>
is specified as an empty string then I<$toplevel> is marked as not
being a transient window any more.  If I<master> is specified,
then the method returns an empty string.  Otherwise the method
returns the path name of I<$toplevel>'s current master, or an
empty string if I<$toplevel> isn't currently a transient window.

=item I<$toplevel>-E<gt>B<withdraw>

Arranges for I<$toplevel> to be withdrawn from the screen.  This
causes the window to be unmapped and forgotten about by the window
manager.  If the window
has never been mapped, then this method
causes the window to be mapped in the withdrawn state.  Not all
window managers appear to know how to handle windows that are
mapped in the withdrawn state.
Note: it sometimes seems to be necessary to withdraw a
window and then re-map it (e.g. with B<deiconify>) to get some
window managers to pay attention to changes in window attributes
such as group.

=item I<$toplevel>-E<gt>B<wrapper>

Returns a list of two elements: the window id of the wrapper window in
which Tk has placed I<$toplevel>, and the height of the menu bar. The
id is the one by which window manager will know I<$toplevel>, and so
is appropriate place to add X properties. The menu height is only
returned on X. On Windows, this value is always zero.

=back

=head1 ICON SIZES

The sizes of bitmaps/images that can be used as icons in this manner are platform
and window manager dependent. Unix window managers are typically more tolerant
than Win32. It is possible that coloured C<iconimage> icons may cause problems
on some X window managers.

=over 4

=item * Win32

C<iconimage> and C<iconbitmap> set the "large" icon, which should be
32x32, it will automatically be scaled down to 16x16 for use as a small icon.
Win32 ignores C<iconwin> requests.

=item * KDE's "kwm"

Accepts coloured C<iconimage> and black and white C<iconbitmap> but
will scale either to a small (14x14?) icon. Kwm ignores C<iconwin>.

=item * Sun's "olwm" or "olvwm"

Honours C<iconwin> which will override C<iconimage> or C<iconbitmap>.
Coloured images work.

=item * Sun's CDE window manager

Coloured images work. ...

=back

=head1 GEOMETRY MANAGEMENT

By default a top-level window appears on the screen in its
I<natural size>, which is the one determined internally by its
widgets and geometry managers.
If the natural size of a top-level window changes, then the window's size
changes to match.
A top-level window can be given a size other than its natural size in two ways.
First, the user can resize the window manually using the facilities
of the window manager, such as resize handles.
Second, the application can request a particular size for a
top-level window using the B<geometry> method.
These two cases are handled identically by Tk;  in either case,
the requested size overrides the natural size.
You can return the window to its natural by invoking B<geometry>
with an empty I<geometry> string.

Normally a top-level window can have any size from one pixel in each
dimension up to the size of its screen.
However, you can use the B<minsize> and B<maxsize> methods
to limit the range of allowable sizes.
The range set by B<minsize> and B<maxsize> applies to
all forms of resizing, including the window's natural size as
well as manual resizes and the B<geometry> method.
You can also use the method B<resizable> to completely
disable interactive resizing in one or both dimensions.

=head1 GRIDDED GEOMETRY MANAGEMENT

Gridded geometry management occurs when one of the widgets of an
application supports a range of useful sizes.
This occurs, for example, in a text editor where the scrollbars,
menus, and other adornments are fixed in size but the edit widget
can support any number of lines of text or characters per line.
In this case, it is usually desirable to let the user specify the
number of lines or characters-per-line, either with the
B<geometry> method or by interactively resizing the window.
In the case of text, and in other interesting cases also, only
discrete sizes of the window make sense, such as integral numbers
of lines and characters-per-line;  arbitrary pixel sizes are not useful.

Gridded geometry management provides support for this kind of
application.
Tk (and the window manager) assume that there is a grid of some
sort within the application and that the application should be
resized in terms of I<grid units> rather than pixels.
Gridded geometry management is typically invoked by turning on
the B<setGrid> option for a widget;  it can also be invoked
with the B<wmGrid> method or by calling B<Tk_SetGrid>.
In each of these approaches the particular widget (or sometimes
code in the application as a whole) specifies the relationship between
integral grid sizes for the window and pixel sizes.
To return to non-gridded geometry management, invoke
B<grid> with empty argument strings.

When gridded geometry management is enabled then all the dimensions specified
in B<minsize>, B<maxsize>, and B<geometry> methods
are treated as grid units rather than pixel units.
Interactive resizing is also carried out in even numbers of grid units
rather than pixels.

=head1 BUGS

Most existing window managers appear to have bugs that affect the
operation of the B<wm> methods.  For example, some changes won't
take effect if the window is already active:  the window will have
to be withdrawn and de-iconified in order to make the change happen.

=head1 SEE ALSO

L<Tk::Widget|Tk::Widget>
L<Tk::tixWm|Tk::tixWm>
L<Tk::Mwm|Tk::Mwm>

=head1 KEYWORDS

aspect ratio, deiconify, focus model, geometry, grid, group, icon, iconify, increments, position, size, title, top-level window, units, window manager

=cut

