Ubuntu Manpage: X11::Protocol::WM -- window manager things for client programs

Provided by: libx11-protocol-other-perl_30-1_all

NAME

       X11::Protocol::WM -- window manager things for client programs

SYNOPSIS

        use X11::Protocol::WM;

DESCRIPTION

       This is some window manager related functions for use by client programs, as per the
       "Inter-Client Communication Conventions Manual" and some of the Net-WM "Extended Window
       Manager Hints".

           /usr/share/doc/xorg-docs/specs/ICCCM/icccm.txt.gz

           <http://www.freedesktop.org/wiki/Specifications/wm-spec>

   Usual Properties
       Every toplevel client window should usually

       •   "set_wm_class()" to identify itself to other programs (see "WM_CLASS" below).

       •   "set_wm_name()" and "set_wm_icon_name()" for user-visible window name (see "WM_NAME,
           WM_ICON_NAME" below).

       •   "set_wm_client_machine_from_syshostname()" and "set_net_wm_pid()" for the running
           process (see "WM_CLIENT_MACHINE" and "_NET_WM_PID" below).

       Then optionally,

       •   If you have an icon then "set_wm_hints()" with a bitmap or a window (see "WM_HINTS"
           below).

       •   If the user gave an initial size or position on the command line then
           "set_wm_normal_hints()".  The same if the program has min/max sizes or aspect ratio
           desired (see "WM_NORMAL_HINTS" below).

       •   If a command to re-run the program can be constructed then "set_wm_command()", and
           preferably keep that up-to-date with changes such as currently open file etc (see
           "WM_COMMAND" below).

FUNCTIONS

Text Properties
Property functions taking text strings such as "set_wm_name()" accept either byte strings
or wide char strings (Perl 5.8 up). Byte strings are presumed to be Latin-1 and set as
"STRING" type in properties. Wide char strings are stored as "STRING" if entirely
Latin-1, or encoded to "COMPOUND_TEXT" for other chars (see Encode::X11).

In the future perhaps the string functions could accept some sort of compound text object
to represent segments of various encodings to become "COMPOUND_TEXT", together with
manipulations for such content etc. If text is bytes in one of the ICCCM encodings then
it might save work to represent it directly as "COMPOUND_TEXT" segments rather than going
to wide chars and back again.

"set_text_property ($X, $window, $prop, $str)"
Set the given $prop (integer atom) property on $window (integer XID) using either
"STRING" or "COMPOUND_TEXT" as described above. If $str is "undef" then $prop is
deleted.

$str is limited to "$X->maximum_request_length()". In theory longer strings can be
stored by piecewise, but there's no attempt to do that here. The maximum request
limit is at least 16384 bytes and the server may allow more, possibly much more.

WM_CLASS
"X11::Protocol::WM::set_wm_class ($X, $window, $instance, $class)"
Set the "WM_CLASS" property on $window (an XID).

This property may be used by the window manager to lookup settings and preferences for
the program through the X Resource system (see "RESOURCES" in X(7)) or similar.

Usually the instance name is the program command such as "xterm" and the class name
something like "XTerm". Some programs have command line options to set the class
and/or instance so the user can have different window manager settings applied to a
particular running copy of a program.

X11::Protocol::WM::set_wm_class ($X, $window,
"myprog", "MyProg");

$instance and $class must be ASCII or Latin-1 only. Wide-char strings which are
Latin-1 are converted as necessary.

WM_CLIENT_MACHINE
"X11::Protocol::WM::set_wm_client_machine ($X, $window, $hostname)"
Set the "WM_CLIENT_MACHINE" property on $window to $hostname (a string).

$hostname should be the name of the client machine as seen from the server. If
$hostname is "undef" then the property is deleted.

Usually a machine name is ASCII-only, but anything per "Text Properties" above is
accepted.

"X11::Protocol::WM::set_wm_client_machine_from_syshostname ($X, $window)"
Set the "WM_CLIENT_MACHINE" property on $window using the Sys::Hostname module.

If "Sys::Hostname" can't determine a hostname by its various gambits then currently
the property is deleted. Would it be better to leave it unchanged, or return a flag
to say if set?

Some of the "Sys::Hostname" cases might return "localhost". That's put through
unchanged, on the assumption that it would be when there's no networking beyond the
local host so client and server are on the same machine and name "localhost" suffices.

WM_COMMAND
"X11::Protocol::WM::set_wm_command ($X, $window, $command, $arg...)"
Set the "WM_COMMAND" property on $window (an XID).

This should be a program name and argument strings which will restart the client.
$command is the program name, followed by any argument strings.

X11::Protocol::WM::set_wm_command ($X, $window,
'myprog',
'--option',
'filename.txt');

A client can set this at any time, or if participating in the "WM_SAVE_YOURSELF"
session manager protocol then it should set in response to a "ClientMessage" of
"WM_SAVE_YOURSELF" .

The command should start the client in its current state as far as possible, so the
command might include a filename, command line options for current settings, etc.

Non-ASCII is allowed per "Text Properties" above. The ICCCM spec is for Latin-1 to
work on a POSIX Latin-1 system, but how well anything else survives a session manager
etc is another matter.

WM_ICON_SIZE
"($min_width,$min_height, $max_width,$max_height, $width_inc,$height_inc) =
X11::Protocol::WM::get_wm_icon_size($X,$root)"
Return the window manager's "WM_ICON_SIZE" recommended icon sizes (in pixels) as a
range, and increment above the minimum. If there's no "WM_ICON_SIZE" property then
return an empty list.

$root is the root window to read. If omitted then read the "$X->root" default.

An icon pixmap or window in "WM_HINTS" should be a size in this range. Many window
managers don't set a preferred icon size. 32x32 might be typical on a small screen or
48x48 on a bigger screen.

WM_HINTS
"X11::Protocol::WM::set_wm_hints ($X, $window, key=>value, ...)"
Set the "WM_HINTS" property on $window (an XID). For example,

X11::Protocol::WM::set_wm_hints
($X, $my_window,
input => 1,
initial_state => 'NormalState',
icon_pixmap => $my_pixmap);

The key/value parameters are as follows.

input integer 0 or 1
initial_state enum string or number
icon_pixmap pixmap (XID integer), depth 1
icon_window window (XID integer)
icon_x \ integer coordinate
icon_y / integer coordinate
icon_mask pixmap (XID integer)
window_group window (XID integer)
urgency boolean

"input" is 1 if the client wants the window manager to give $window the keyboard input
focus. This will be with "$X->SetInputFocus()", or if "WM_TAKE_FOCUS" is in
"WM_PROTOCOLS" then instead by a "ClientMessage".

"input" is 0 if the window manager should not give the client the focus. This is
either because $window is output-only, or if "WM_TAKE_FOCUS" is in "WM_PROTOCOLS" then
because the client will do a "SetInputFocus()" to itself on an appropriate button
press etc.

"initial_state" is a string or number. The ICCCM allows "NormalState" or
"IconicState" as initial states.

"NormalState" 1
"IconicState" 3

"icon_pixmap" should be a bitmap, ie. a pixmap (XID) with depth 1. The window manager
will draw it in suitable contrasting colours. "1" pixels are foreground and "0" is
background. "icon_mask" bitmap is applied to the displayed icon. It can be used to
make a non-rectangular icon.

"icon_window" is a window which the window manager may show when $window is iconified.
This can be used for a multi-colour icon, done either by a background or by client
drawing (in response to "Expose" events, or updated periodically for a clock, etc).
The "icon_window" should be a child of the root and should use the default visual and
colormap of the screen. The window manager might resize the window and/or border.

The window manager might set a "WM_ICON_SIZE" property on the root window for good
icon sizes. See "WM_ICON_SIZE".

"window_group" is the XID of a window which is the group leader of a group of top-
level windows being used by the client. The window manager might provide a way to
manipulate the group as a whole, for example to iconify it all. If iconified then the
icon hints of the leader are used for the icon. The group leader can be an unmapped
window. It can be convenient to use a never-mapped window as the leader for all
subsequent windows.

"urgency" true means the window is important and the window manager should draw the
user's attention to it in some way. The client can change this hint at any time to
change the current importance.

"(key => $value, ...) = X11::Protocol::WM::get_wm_hints ($X, $window)"
Return the "WM_HINTS" property from $window. The return is a list of key/value pairs
as per "set_wm_hints()" above

input => 1,
icon_pixmap => 1234,
...

Only fields with their flag bits set in the hints are included in the return. If
there's no "WM_HINTS" at all or or its flags field is zero then the return is an empty
list.

The return can be put into a hash to get fields by name,

my %hints = X11::Protocol::WM::get_wm_hints ($X, $window);
if (exists $hints{'icon_pixmap'}) {
print "icon_pixmap is ", $hints{'icon_pixmap'}, "\n";
}

"initial_state" is a string such as "NormalState". The pixmaps and windows are string
"None" if set but zero (which is probably unusual). If "$X->{'do_interp'}" is
disabled then all are numbers.

X11R2 Xlib had a bug in its "XSetWMHints()" which chopped off the "window_group" value
from the hints stored. The "window_group" field is omitted from the return in that
case.

"(key => $value, ...) = X11::Protocol::WM::change_wm_hints ($X, $window, key=>value, ...)"
Change some fields of the "WM_HINTS" property on $window. The given key/value fields
are changed. Other fields are left alone. For example,

X11::Protocol::WM::set_wm_hints ($X, $window,
urgency => 1);

A value "undef" means delete a field,

X11::Protocol::WM::set_wm_hints ($X, $window,
icon_pixmap => undef,
icon_mask => undef);

The change requires a server round-trip to fetch the current values from $window. An
application might prefer to remember its desired hints and send a full
"set_wm_hints()" each time.

"$bytes = X11::Protocol::WM::pack_wm_hints ($X, key=>value...)"
Pack a set of values into a byte string of "WM_HINTS" format. The key/value arguments
are per "set_wm_hints()" above and the result is the raw bytes stored in a "WM_HINTS"
property.

The $X argument is not actually used currently, but is present in case "initial_state"
or other values might use an "$X->num()" lookup in the future.

"(key => $value, ...) = X11::Protocol::WM::unpack_wm_hints ($X, $bytes)"
Unpack a byte string as a "WM_HINTS" structure. The return is key/value pairs as per
"get_wm_hints()" above. The $X parameter is used for "do_interp". There's no
communication with the server.

WM_NAME, WM_ICON_NAME
"X11::Protocol::WM::set_wm_name ($X, $window, $name)"
Set the "WM_NAME" property on $window (an integer XID) to $name (a string).

The window manager might display this as a title above the window, or in a menu of
windows, etc. It can be a Perl 5.8 wide-char string per "Text Properties" above. A
good window manager ought to support non-ASCII or non-Latin-1 titles, but how well it
displays might depend on fonts etc.

"X11::Protocol::WM::set_wm_icon_name ($X, $window, $name)"
Set the "WM_ICON_NAME" property on $window (an integer XID) to $name (a string).

The window manager might display this when $window is iconified. If $window doesn't
have an icon (in "WM_HINTS" or from the window manager itself) then this text might be
all that's shown. Either way it should be something short. It can be a Perl 5.8
wide-char string per "Text Properties" above.

WM_NORMAL_HINTS
"X11::Protocol::WM::set_wm_normal_hints ($X, $window, key=>value,...)"
Set the "WM_NORMAL_HINTS" property on $window (an integer XID). This is a
"WM_SIZE_HINTS" structure which tells the window manager what sizes the client would
like. For example,

set_wm_normal_hints ($X, $window,
min_width => 200,
min_height => 100);

Generally the window manager restricts user resizing to the hint limits. Most window
managers use these hints, but of course they're only hints and a good program should
be prepared for other sizes even if it won't look good or can't do much useful when
too big or too small etc.

The key/value parameters are

user_position boolean, window x,y is user specified
user_size boolean, window width,height is user specified
program_position boolean, window x,y is program specified
program_size boolean, window width,height is program specified
min_width \ integers, min size in pixels
min_height /
max_width \ integers, max size in pixels
max_height /
base_width \ integers, size base in pixels
base_height /
width_inc \ integers, size increment in pixels
height_inc /
min_aspect \ fraction 2/3 or decimal 2 or 1.5
min_aspect_num | or integer num/den up to 0x7FFFFFFF
min_aspect_den |
max_aspect |
max_aspect_num |
max_aspect_den /
win_gravity WinGravity enum "NorthEast" etc

"user_position" and "user_size" are flags meaning that the window's x,y or
width,height (in the usual core "$X->SetWindowAttributes()") were given by the user,
for example from a "-geometry" command line option. The window manager will generally
obey these values and skip any auto-placement or interactive placement it might
otherwise do.

"program_position" and "program_size" are flags meaning the window x,y or width,height
were calculated by the program. The window manager might override with its own
positioning or sizing policy. There's generally no need to set these fields unless
the program has a definite idea of where and how big it should be. For a size it's
enough to set the core window width,height and let the window manager (if there's one
running) go from there.

Items shown grouped above must be given together, so for instance if a "min_width" is
given then "min_height" should be given too.

"base_width","base_height" and "width_inc","height_inc" ask that the window be a
certain base size in pixels then a multiple of "inc" pixels above that. This can be
used by things like "xterm" which want a fixed size for border or scrollbar and then a
multiple of the character size above that. If "base_width","base_height" are not
given then "min_width","min_height" is the base size.

"base_width","base_height" can be smaller than "min_width","min_height". This means
the size should still be a base+inc multiple, but the first such which is at least the
min size. The window manager generally presents the "inc" multiple to the user, so
that for example on an xterm the user sees a count of characters. A min size can then
demand for example a minimum 1x1 or 2x2 character size.

"min_aspect","max_aspect" ask that the window have a certain minimum or maximum
width/height ratio. For example aspect 2/1 means it should be twice as wide as it is
high. This is applied to the size above "base_width","base_height", or if base not
given then to the whole window size.

"min_aspect_num","min_aspect_den" and "max_aspect_num","max_aspect_den" set numerator
and denominator values directly (INT32, so maximum 0x7FFF_FFFF). Or "min_aspect" and
"max_aspect" accept a single value in various forms which are turned into num/den
values.

2 integer
1.125 decimal, meaning 1125/1000
2/3 fraction
1.5/4.5 fraction with decimals

Values bigger than 0x7FFFFFFF in these forms are reduced proportionally as necessary.
A Perl floating point value will usually have more bits of precision than 0x7FFFFFFF
and is truncated to something that fits.

"win_gravity" is how the client would like to be shifted to make room for any
surrounding frame the window manager might add. For example if the program calculated
the window size and position to ensure the north-east corner is at a desired position,
then give "win_gravity => "NorthEast"" so that the window manager keeps the north-east
corner the same when it applies its frame.

"win_gravity => "Static"" means the frame is put around the window and the window not
moved at all. Of course that might mean some of the frame ends up off-screen.

"$bytes = X11::Protocol::WM::pack_size_hints ($X, key=>value,...)"
Return a bytes string which is a "WM_SIZE_HINTS" structure made from the given
key/value parameters. "WM_SIZE_HINTS" is structure type for "WM_NORMAL_HINTS"
described above and the key/value parameters are as described above.

The $X parameter is used to interpret "win_gravity" enum values. There's no
communication with the server.

"($num,$den) = X11::Protocol::WM::aspect_to_num_den ($aspect)"
Return a pair of INT32 integers 0 to 0x7FFF_FFFF for the given aspect ratio $aspect.
This is the conversion applied to "min_aspect" and "max_aspect" above. $aspect can be
any of the integer, decimal or fraction described.

WM_PROTOCOLS
"X11::Protocol::WM::set_wm_protocols ($X, $window, $protocol,...)"
Set the "WM_PROTOCOLS" property on $window (an XID). Each argument is a string
protocol name or an integer atom ID.

X11::Protocol::WM::set_wm_protocols
($X, $window, 'WM_DELETE_WINDOW', '_NET_WM_PING')

For example "WM_DELETE_WINDOW" means that when the user clicks the close button the
window manager sends a "ClientMessage" event rather than doing a "KillClient()". The
"ClientMessage" event allows a program to clean-up or ask the user about saving a
document before exiting, etc.

WM_STATE
The window manager maintains a state for each client window it manages,

WithdrawnState
NormalState
IconicState

"WithdrawnState" means the window is not mapped and the window manager is not managing it.
A newly created window ("$X->CreateWindow()") is initially "WithdrawnState" and on first
"$X->MapWindow()" goes to "NormalState" (or to "IconicState" if that's the initial state
asked for in "WM_HINTS").

"iconify()" and "withdraw()" below can change the state to iconic or withdrawn. A window
can be restored from iconic to normal by a "MapWindow()".

"($state, $icon_window) = X11::Protocol::WM::get_wm_state ($X, $window)"
Return the "WM_STATE" property from $window. This is set by the window manager on
top-level application windows. If there's no such property then the return is an
empty list.

$state returned is an enum string, or an integer value if "$X->{'do_interp'}" is
disabled or the value unrecognised.

"WithdrawnState" 0 not displayed
"NormalState" 1 window displayed
"IconicState" 3 iconified in some way

"ZoomState" 2 \ no longer in ICCCM
"InactiveState" 4 / (zoom meant maximized)

$icon_window returned is the window (integer XID) used by the window manager to
display an icon of $window. If there's no such window then $icon_window is "None" (or
0 if "$X->{'do_interp'}" is disabled).

$icon_window might be the icon window from the client's "WM_HINTS" or it might be a
window created by the window manager. The client can draw into it for animations etc,
perhaps selecting "Expose" events on it to know when to redraw.

"WM_STATE" is set by the window manager when a toplevel window is first mapped (or
perhaps earlier), and then kept up-to-date. Generally no "WM_STATE" property or a
"WM_STATE" set to WithdrawnState means the window manager is not managing the window,
or not yet doing so. A client can select "PropertyChange" event mask in the usual way
to listen for "WM_STATE" changes.

"($state, $icon_window) = X11::Protocol::WM::unpack_wm_state ($X, $bytes)"
Unpack the bytes of a "WM_STATE" property to a $state and $icon_window as per
"get_wm_state()" above.

$X is used for "$X->{'do_interp'}" but there's no communication with the server.

"X11::Protocol::WM::iconify ($X, $window)"
"X11::Protocol::WM::iconify ($X, $window, $root)"
Change $window to "IconicState" by sending a "ClientMessage" to the window manager.

If the window manager does not have any iconification then it might do nothing (eg.
some tiling window managers). If there's no window manager running then iconification
is not possible and this message will do nothing.

$root should be the root window of $window. If not given or "undef" then it's
obtained from a "QueryTree()". Any client can iconify any top level window.

If $window has other windows which are "WM_TRANSIENT_FOR" for it then generally the
window manager will iconify or hide those windows too (see "WM_TRANSIENT_FOR" below).

"X11::Protocol::WM::withdraw ($X, $window)"
"X11::Protocol::WM::withdraw ($X, $window, $root)"
Change $window to "WithdrawnState" by an "$X->UnmapWindow()" and a synthetic
"UnmapNotify" message to the window manager.

If there's no window manager running then the "UnmapWindow()" unmaps and the
"UnmapNotify" message does nothing.

$root should be the root window of $window. If not given or "undef" then it's
obtained from a "$X->QueryTree()".

If other windows are "WM_TRANSIENT_FOR" this $window (eg. open dialog windows) then
generally the client should withdraw them too. The window manager might make such
other windows inaccessible anyway.

The ICCCM specifies an "UnmapNotify" message so the window manager is notified of the
desired state change even if $window is already unmapped, such as in "IconicState" or
perhaps during some window manager reparenting, etc.

$window can be changed back to NormalState or IconicState later with "$X->MapWindow()"
the same as for a newly created window. (And "WM_HINTS" "initial_state" can give a
desired initial iconic/normal state). But before doing so be sure the window manager
has recognised the "withdraw()". This will be when the window manager changes the
"WM_STATE" property to "WithdrawnState", or deletes that property.

Any client can withdraw any toplevel window, but it's unusual for a client to withdraw
windows which are not its own.

WM_TRANSIENT_FOR
"X11::Protocol::WM::set_wm_transient_for ($X, $window, $transient_for)"
Set the "WM_TRANSIENT_FOR" property on $window (an XID).

$transient_for is another window XID, or "undef" if $window is not transient for
anything so "WM_TRANSIENT_FOR" should be deleted.

"Transient for" means $window is some sort of dialog or menu related to the given
$transient_for window. The window manager will generally iconify $window together
with its $transient_for, etc. See "set_motif_wm_hints()" below for "modal"
transients.

_MOTIF_WM_HINTS
"X11::Protocol::WM::set_motif_wm_hints ($X, $window, key=>value...)"
Set the "MOTIF_WM_HINTS" property on $window (an XID).

These hints control window decorations and "modal" state. It originated in the Motif
"mwm" window manager but is recognised by most other window managers. It should be
set on a toplevel window before mapping. Changes made later might not affect what the
window manager does.

X11::Protocol::WM::set_motif_wm_hints
($X, $dialog_window,
input_mode => "full_application_modal");
$X->MapWindow ($dialog_window);

Ordinary windows generally don't need to restrict their decorations etc, but something
special like a clock or gadget might benefit.

X11::Protocol::WM::set_motif_wm_hints
($X, $my_gadget_window,
functions => 4+32, # move+close
decorations => 1+4+8); # border+title+menu

The key/value arguments are

functions => integer bits
decorations => integer bits
input_mode => enum string or integer
status => integer bits

"functions" is what actions the window manager should offer to the user in a drop-down
menu or similar. It's an integer bitwise OR of the following values. If not given
then the default is normally all functions.

bit actions offered
--- ---------------
1 all functions
2 resize window
4 move window
8 minimize, to iconify
16 maximize, to full-screen (with a frame still)
32 close window

"decorations" is what visual decorations the window manager should show around the
window. It's an integer bitwise OR of the following values. If not given then the
default is normally all decorations.

bit decorations displayed
--- ---------------------
1 all decorations
2 border around the window
4 resizeh, handles to resize by dragging
8 title bar, showing WM_NAME
16 menu, drop-down menu of the "functions" above
32 minimize button, to iconify
64 maximize button, to full-screen

"input_mode" allows a window to be "modal", meaning the user should interact only with
$window. The window manager will generally keep it on top, not move the focus to
other windows, etc. The value is one of the following strings or corresponding
integer,

string integer
"modeless" 0 not modal (the default)
"primary_application_modal" 1 modal to its "transient for"
"system_modal" 2 modal to the whole display
"full_application_modal" 3 modal to the current client

"primary_application_modal" means $window is modal for the "WM_TRANSIENT_FOR" set on
$window (see "WM_TRANSIENT_FOR" above), but other windows on the display can be used
normally. "full_application_modal" means modal for all windows of the same client,
but other clients can be used normally.

Modal behaviour is important for good user interaction and therefore ought to be
implemented by a window manager, but a good program should be prepared to do something
with input on other windows.

"status" field is a bitwise OR of the following bits (only one currently).

bit
1 tearoff menu window

Tearoff menu flag is intended for tearoff menus, as the name suggests.

X11::Protocol::WM::set_motif_wm_hints
($X, $my_tearoff_window, status => 1);

Motif "mwm" will expand the window to make it wide enough for the "WM_NAME" in the
frame title bar. Otherwise a title is generally truncated to as much as fits the
window's current width. Expanding can be good for tearoffs where the title bar is
some originating item name etc which the user should see. But don't be surprised if
this flag is ignored by other window managers.

Perhaps in the future the individual bits above will have some symbolic names. Either
constants or string values interpreted. What would a possible "get_hints()" return,
and what might be convenient to add/subtract bits?

See /usr/include/Xm/MwmUtil.h on the hints bits, and see "mwm" sources WmWinInfo.c
"ProcessWmWindowTitle()" for the "status" tearoff window flag.

_NET_FRAME_EXTENTS
"my ($left,$right, $top,$bottom) = X11::Protocol::WM::get_net_frame_extents ($X, $window)"
Get the "_NET_FRAME_EXTENTS" property from $window.

This is set on top-level windows by the window manager to report how many pixels of
frame or decoration it has added around $window.

If there's no such property set then the return is an empty list. So for example

my ($left,$right,$top,$bottom)
= get_net_frame_extents ($X, $window)
or print "no frame extents";

my ($left,$right,$top,$bottom)
= get_net_frame_extents ($X, $window);
if (! defined $left) {
print "no frame extents";
}

A client might look at the frame size if moving a window programmatically so as not to
put the title bar etc off-screen. Oldish window managers might not provide this
information though.

_NET_WM_PID
"X11::Protocol::WM::set_net_wm_pid ($X, $window)"
"X11::Protocol::WM::set_net_wm_pid ($X, $window, $pid)"
"X11::Protocol::WM::set_net_wm_pid ($X, $window, undef)"
Set the "_NET_WM_PID" property on $window to the given $pid process ID, or to the $$
current process ID if omitted. (See perlvar for $$.) If $pid is "undef" then the
property is deleted.

A window manager or similar might use the PID to forcibly kill an unresponsive client.
It's only useful if "WM_CLIENT_MACHINE" (above) is set too, to know where the client
is running.

_NET_WM_STATE
An EWMH compliant window manager maintains a set of state flags for each client window. A
state is an atom such as "_NET_WM_STATE_FULLSCREEN" and each such state can be present or
absent. The supported states are listed in "_NET_SUPPORTED". Any client can ask the
window manager to change states on any window. A client might be able to ask for an
initial set of states for a new window (see "set_net_wm_state()" below). Possible states
include

_NET_WM_STATE_MODAL
The window is modal to its "WM_TRANSIENT_FOR" parent or if "WM_TRANSIENT_FOR" not set
then modal to its window group.

See "_MOTIF_WM_HINTS" to set modal with the Motif style hints.

_NET_WM_STATE_STICKY
The window is kept in a fixed position on screen when the desktop scrolls.

_NET_WM_STATE_MAXIMIZED_VERT
_NET_WM_STATE_MAXIMIZED_HORZ
The window is maximum size vertically or horizontally or both. The window still has
its surrounding decoration and the size should obey size increments specified in
"WM_NORMAL_HINTS".

_NET_WM_STATE_FULLSCREEN
The window is the full screen with no decoration around it, thus being the full
screen.

The window manager remembers the "normal" size of the window so that when maximize or
fullscreen state is removed the previous size is restored.

_NET_WM_STATE_SHADED
The window is "shaded" which generally means its title bar is displayed but none of
the client window. This is an alternative to iconifying a window.

_NET_WM_STATE_SKIP_TASKBAR
_NET_WM_STATE_SKIP_PAGER
Don't show the window on a task bar or in a pager, respectively.

_NET_WM_STATE_HIDDEN (read-only)
This state is set by the window manger when the window is iconified or similar and so
does not appear on screen. Clients cannot change this.

_NET_WM_STATE_ABOVE
_NET_WM_STATE_BELOW
The window is kept above or below other client windows. The stacking order maintained
is roughly

_NET_WM_STATE_DEMANDS_ATTENTION
The window should be brought to the attention of the user in some way. A client sets
this and the window manager clears it after the window has received user attention
(which might mean keyboard focus or similar).

The following functions get or set the states.

"change_net_wm_state($X, $window, $action, $state, key=>value,...)"
Change one of the "_NET_WM_STATE" state flags on $window by sending a message to the
window manager. For example,

change_net_wm_state ($X, $window, "toggle", "FULLSCREEN");

$window must be a managed window, ie. must have had its initial "MapWindow()" and not
be an override-redirect. If that's not so or if there's no window manager or it
doesn't have EWMH then this change message will have no effect.

$action is a string or integer how to change the state,

"remove" 0
"add" 1
"toggle" 2

$state is a string such as "FULLSCREEN" or an atom integer such as
"$X->atom("_NET_WM_STATE_FULLSCREEN")".

The further optional key/value parameters are

state2 => string or atom
source => "none", "normal", "user", 0,1,2
root => integer XID, or undef

A change message can act on one or two states. For two states the second is "state2".
For example to maximize vertically and horizontally in one operation,

change_net_wm_state ($X, $window, "add", "MAXIMIZED_VERT",
state2 => "MAXIMIZED_HORZ");

"source" is where the change request came from. The default is "normal" which means a
normal application. "user" is for a user-interface control program such as a pager.
("none"=0 is what clients prior to EWMH 1.2 gave.)

"root" is the root window (integer XID) of $window. If "undef" or not given then it's
found with "$X->QueryTree()". If you already know the root then giving it avoids that
round-trip query.

"@strings = get_net_wm_state ($X, $window)"
"@atoms = get_net_wm_state_atoms ($X, $window)"
Get the "_NET_WM_STATE" property from $window. "get_net_wm_state()" returns a list of
strings such as "FULLSCREEN". "get_net_wm_state_atoms()" returns a list of atom
integers such as "$X->atom('_NET_WM_STATE_FULLSCREEN')". In both cases if there's no
such property or if it's empty then return an empty list.

"set_net_wm_state ($X, $window, $state,...)"
Set the "_NET_WM_STATE" property on $window. Each $state can be a string such as
"FULLSCREEN" or an atom integer such as "$X->atom('_NET_WM_STATE_FULLSCREEN')".

A client can set "_NET_WM_STATE" on a new window to tell the window manager of desired
initial states. However this is only a "should" in the EWMH spec so it might not be
obeyed.

# initial desired state
set_net_wm_state ($X, $window,
"MAXIMIZED_HORZ", "MAXIMIZED_VERT");

After the window is managed by the window manager (once mapped) clients should not set
"_NET_WM_STATE" but instead ask the window manager with "change_net_wm_state()" per
above.

_NET_WM_USER_TIME
"set_net_wm_user_time ($X, $window, $time)"
Set the "_NET_WM_USER_TIME" property on $window.

$time should be a server time value (an integer) from the last user keypress etc event
in $window. Or when $window is created then the time from the event which caused it
to be opened.

On a newly created window a special $time value 0 means the window should not receive
the focus when mapped -- assuming the window manager recognises "_NET_WM_USER_TIME" of
course.

If the client has the active window it should update "_NET_WM_USER_TIME" for every
user input. Generally KeyPress and ButtonPress events are user input, but KeyRelease
and ButtonRelease are not since it's the Press events which are the user actively
doing something.

The window manager might use "_NET_WM_USER_TIME" to control focus and/or stacking
order so that for example a slow popup doesn't steal the focus if you've gone to
another window to do other work in the interim.

_NET_WM_WINDOW_TYPE
"X11::Protocol::WM::set_net_wm_window_type ($X, $window, $window_type)"
Set the "_NET_WM_WINDOW_TYPE" property on $window (an XID). $window_type can be a
type string as follows from the EWMH,

"NORMAL"
"DIALOG"
"DESKTOP"
"DOCK"
"TOOLBAR"
"MENU"
"UTILITY"
"SPLASH"

$window_type can also be an integer atom such as
"$X->atom('_NET_WM_WINDOW_TYPE_DIALOG')".

Frame to Client
"$window = X11::Protocol::WM::frame_window_to_client ($X, $frame)"
Return the client window (XID) contained within window manager $frame window (an XID).
$frame is usually an immediate child of the root window.

If no client window can be found in $frame then return "undef". This might happen if
$frame is an icon window or similar created by the window manager itself, or an
override-redirect client without a frame, or if there's no window manager running at
all. In the latter two cases $frame would be the client already.

The strategy is to look at $frame and down the window tree seeking a "WM_STATE"
property which the window manager puts on a client's toplevel when mapped. The search
depth and total windows are limited in case the window manager does its decoration in
some ridiculous way or the client uses excessive windows (which would be traversed if
there's no window manager).

+-rootwin--------------------------+
| |
| |
| +-frame-win--------+ |
| | +-client-win---+ | |
| | | WM_STATE ... | | |
| | | | | |
| | +--------------+ | |
| +------------------+ |
| |
+----------------------------------+

Care is taken not to error out if some windows are destroyed during the search. The
windows may belong to other clients and could be destroyed at any time. If $frame
itself doesn't exist then the return is "undef".

This function is similar to what "xwininfo" and similar programs do to go from a
toplevel root window child down to the client window, per dmsimple.c "Select_Window()"
or Xlib "XmuClientWindow()". (See also X11::Protocol::ChooseWindow.)

Virtual Root
Some window managers use a "virtual root" window covering the entire screen. Application
windows or frame windows are then children of that virtual root. This can help the window
manager implement a large desktop or multiple desktops, though it tends to fail in subtle
ways with various root oriented programs, including for example xsetroot(1) or the click-
to-select in xwininfo(1) and xprop(1).

"$window = X11::Protocol::WM::root_to_virtual_root ($X, $root)"
If the window manager is using a virtual root then return that window XID. If not
then return "undef".

The current implementation searches for a window with an "__SWM_VROOT" property, as
per the "swm", "tvtwm" and "amiwm" window managers, and as used by the "xscreensaver"
program and perhaps some versions of KDE.

There's nothing yet for EWMH "_NET_VIRTUAL_ROOTS". Do any window managers use it? Is
"_NET_CURRENT_DESKTOP" an index into that virtual roots list?

(See X11::Protocol::XSetRoot for changing the background of a root or virtual root.)

EXPORTS

       Nothing is exported by default, but the functions can be requested in usual "Exporter"
       style,

           use X11::Protocol::WM 'set_wm_hints';
           set_wm_hints ($X, $window, input => 1, ...);

       Or just call with full package name

           use X11::Protocol::WM;
           X11::Protocol::WM::set_wm_hints ($X, $window, input => 1, ...);

       There's no ":all" tag since this module is meant as a grab-bag of functions and to import
       as-yet unknown things would be asking for name clashes.

BUGS

       Not much attention is paid to text on an EBCDIC system.  Wide char strings probably work,
       but byte strings may go straight through where they ought to be re-coded to Latin-1.  But
       the same probably applies to parts of the core "X11::Protocol" such as "$X->atom_name()"
       where you'd want to convert Latin-1 from the server to native EBCDIC.

HOME PAGE

       <http://user42.tuxfamily.org/x11-protocol-other/index.html>

LICENSE

       Copyright 2011, 2012, 2013, 2014, 2016 Kevin Ryde

       X11-Protocol-Other is free software; you can redistribute it and/or modify it under the
       terms of the GNU General Public License as published by the Free Software Foundation;
       either version 3, or (at your option) any later version.

       X11-Protocol-Other is distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with
       X11-Protocol-Other.  If not, see <http://www.gnu.org/licenses/>.