NAME
       bind - Arrange for X events to invoke Tcl scripts

SYNOPSIS
       bind tag

       bind tag sequence

       bind tag sequence script

       bind tag sequence +script


INTRODUCTION
       The bind command associates Tcl scripts with X events.  If
       all three arguments are specified, bind will  arrange  for
       script  (a  Tcl  script)  to  be  evaluated  whenever  the
       event(s) given by sequence occur in the window(s)  identi-
       fied  by tag.  If script is prefixed with a ``+'', then it
       is appended to any existing binding for sequence;   other-
       wise  script  replaces any existing binding.  If script is
       an empty string then the current binding for  sequence  is
       destroyed,  leaving sequence unbound.  In all of the cases
       where a script argument is provided, bind returns an empty
       string.

       If sequence is specified without a script, then the script
       currently bound to  sequence  is  returned,  or  an  empty
       string  is  returned  if there is no binding for sequence.
       If neither sequence nor  script  is  specified,  then  the
       return  value  is  a  list  whose  elements  are  all  the
       sequences for which there exist bindings for tag.

       The tag argument determines which  window(s)  the  binding
       applies  to.  If tag begins with a dot, as in .a.b.c, then
       it must be the path name for a window; otherwise it may be
       an  arbitrary  string.  Each window has an associated list
       of tags, and a binding applies to a particular  window  if
       its tag is among those specified for the window.  Although
       the bindtags command may be used to  assign  an  arbitrary
       set  of binding tags to a window, the default binding tags
       provide the following behavior:

              If a tag is the name  of  an  internal  window  the
              binding applies to that window.

              If  the  tag  is  the name of a toplevel window the
              binding applies to the toplevel window and all  its
              internal windows.

              If  the tag is the name of a class of widgets, such
              as Button, the binding applies to  all  widgets  in
              that class;
              If  tag  has  the value all, the binding applies to
              all windows in the application.


EVENT PATTERNS
       The sequence argument specifies a sequence of one or  more
       event patterns, with optional white space between the pat-
       terns.  Each event pattern may take either of  two  forms.
       In the simplest case it is a single printing ASCII charac-
       ter, such as a or [.  The character may  not  be  a  space
       character  or  the  character  <.   This  form  of pattern
       matches a KeyPress event  for  the  particular  character.
       The second form of pattern is longer but more general.  It
       has the following syntax:
              <modifier-modifier-type-detail>
       The entire event pattern is surrounded by angle  brackets.
       Inside  the  angle brackets are zero or more modifiers, an
       event type, and an extra  piece  of  information  (detail)
       identifying  a  particular  button  or keysym.  Any of the
       fields may be omitted, as long as at least one of type and
       detail  is present.  The fields must be separated by white
       space or dashes.


MODIFIERS
       Modifiers consist of any of the following values:

              Control                 Mod2, M2
              Shift                   Mod3, M3
              Lock                    Mod4, M4
              Button1, B1             Mod5, M5
              Button2, B2             Meta, M
              Button3, B3             Alt
              Button4, B4             Double
              Button5, B5             Triple
              Mod1, M1

       Where more than one value is listed, separated by  commas,
       the values are equivalent.  Most of the modifiers have the
       obvious X meanings.  For example,  Button1  requires  that
       button  1 be depressed when the event occurs.  For a bind-
       ing to match a given event, the  modifiers  in  the  event
       must  include all of those specified in the event pattern.
       An event may also contain additional modifiers not  speci-
       fied  in the binding.  For example, if button 1 is pressed
       while the shift and control keys  are  down,  the  pattern
       <Control-Button-1>    will    match    the    event,   but
       <Mod1-Button-1> will not.  If no modifiers are  specified,
       then  any  combination  of modifiers may be present in the
       event.

       Meta and M refer to whichever of the M1 through  M5  modi-
       fiers  is  associated with the meta key(s) on the keyboard
       (keysyms Meta_R and Meta_L).  If there are no  meta  keys,
       or  if  they  are  not associated with any modifiers, then
       Meta and M will not match any events.  Similarly, the  Alt
       modifier  refers  to whichever modifier is associated with
       the alt key(s) on the keyboard (keysyms Alt_L and  Alt_R).

       The  Double  and  Triple  modifiers  are a convenience for
       specifying double mouse clicks and other repeated  events.
       They  cause a particular event pattern to be repeated 2 or
       3 times, and also place a time and  space  requirement  on
       the  sequence:  for a sequence of events to match a Double
       or Triple pattern, all of  the  events  must  occur  close
       together  in  time and without substantial mouse motion in
       between.  For example, <Double-Button-1> is equivalent  to
       <Button-1><Button-1>   with   the  extra  time  and  space
       requirement.


EVENT TYPES
       The type field may be any of the standard X  event  types,
       with  a  few  extra abbreviations.  Below is a list of all
       the valid types; where two names appear together, they are
       synonyms.

              ButtonPress, Button Expose             Map
              ButtonRelease       FocusIn            Motion
              Circulate           FocusOut           Property
              Colormap            Gravity            Reparent
              Configure           KeyPress, Key      Unmap
              Destroy             KeyRelease         Visibility
              Enter               Leave


       The last part of a long event specification is detail.  In
       the case of a ButtonPress or ButtonRelease  event,  it  is
       the  number  of  a  button  (1-5).   If a button number is
       given, then only an event on that particular  button  will
       match;  if no button number is given, then an event on any
       button will match.  Note:  giving a specific button number
       is  different  than  specifying  a button modifier; in the
       first case,  it  refers  to  a  button  being  pressed  or
       released, while in the second it refers to some other but-
       ton that is already  depressed  when  the  matching  event
       occurs.   If  a  button  number  is given then type may be
       omitted:  if will default to  ButtonPress.   For  example,
       the specifier <1> is equivalent to <ButtonPress-1>.

       If  the  event type is KeyPress or KeyRelease, then detail
       may be specified in the form of an X keysym.  Keysyms  are
       textual  specifications  for  particular  keys on the key-
       board; they include all the alphanumeric ASCII  characters
       (e.g.  ``a'' is the keysym for the ASCII character ``a''),
       plus   descriptions   for   non-alphanumeric    characters
       (``comma''  is  the  keysym for the comma character), plus
       descriptions for all the non-ASCII keys  on  the  keyboard
       (``Shift_L''  is  the  keysm  for  the left shift key, and
       ``F1'' is the keysym  for  the  F1  function  key,  if  it
       exists).   The  complete  list of keysyms is not presented
       here;  it is available in other X  documentation  and  may
       vary from system to system.  If necessary, you can use the
       %K notation described below to print out the  keysym  name
       for  a  particular key.  If a keysym detail is given, then
       the type field may be omitted;  it will  default  to  Key-
       Press.   For  example,  <Control-comma>  is  equivalent to
       <Control-KeyPress-comma>.


BINDING SCRIPTS AND SUBSTITUTIONS
       The script argument to bind is a Tcl script, which will be
       executed  whenever  the given event sequence occurs.  Com-
       mand will be executed in the  same  interpreter  that  the
       bind  command  was  executed in, and it will run at global
       level (only global  variables  will  be  accessible).   If
       script contains any % characters, then the script will not
       be executed directly.  Instead, a new script will be  gen-
       erated  by  replacing  each %, and the character following
       it, with information from the current event.  The replace-
       ment  depends on the character following the %, as defined
       in  the  list  below.   Unless  otherwise  indicated,  the
       replacement string is the decimal value of the given field
       from the current event.  Some  of  the  substitutions  are
       only  valid for certain types of events;  if they are used
       for other types of events the value substituted  is  unde-
       fined.

       %%   Replaced with a single percent.

       %#   The  number  of  the last client request processed by
            the server (the serial field from the event).   Valid
            for all event types.

       %a   The  above  field from the event, formatted as a hex-
            adecimal number.  Valid only for Configure events.

       %b   The  number  of  the  button  that  was  pressed   or
            released.   Valid  only for ButtonPress and ButtonRe-
            lease events.

       %c   The count field  from  the  event.   Valid  only  for
            Expose events.

       %d   The  detail field from the event.  The %d is replaced
            by a  string  identifying  the  detail.   For  Enter,
            Leave,  FocusIn, and FocusOut events, the string will
            be one of the following:

                   NotifyAncestor          NotifyNonlinearVirtual
                   NotifyDetailNone        NotifyPointer
                   NotifyInferior          NotifyPointerRoot
                   NotifyNonlinear         NotifyVirtual

            For events other than these, the  substituted  string
            is undefined.

       %f   The  focus field from the event (0 or 1).  Valid only
            for Enter and Leave events.

       %h   The height field from the event.  Valid only for Con-
            figure, Expose, and GraphicsExpose events.

       %k   The  keycode  field  from  the event.  Valid only for
            KeyPress and KeyRelease events.

       %m   The mode  field  from  the  event.   The  substituted
            string  is one of NotifyNormal, NotifyGrab, NotifyUn-
            grab, or NotifyWhileGrabbed.  Valid only  for  Enter-
            Window, FocusIn, FocusOut, and LeaveWindow events.

       %o   The  override_redirect  field  from the event.  Valid
            only for Map, Reparent, and Configure events.

       %p   The place field from the event, substituted as one of
            the  strings PlaceOnTop or PlaceOnBottom.  Valid only
            for Circulate events.

       %s   The state field from  the  event.   For  ButtonPress,
            ButtonRelease,  Enter,  KeyPress,  KeyRelease, Leave,
            and Motion events, a decimal string  is  substituted.
            For  Visibility,  one  of the strings VisibilityUnob-
            scured, VisibilityPartiallyObscured, and  Visibility-
            FullyObscured is substituted.

       %t   The time field from the event.  Valid only for events
            that contain a time field.

       %w   The width field from the event.  Valid only for  Con-
            figure, Expose, and GraphicsExpose events.

       %x   The  x  field  from the event.  Valid only for events
            containing an x field.

       %y   The y field from the event.  Valid  only  for  events
            containing a y field.

       %A   Substitutes  the ASCII character corresponding to the
            event, or the empty string if the event doesn't  cor-
            respond to an ASCII character (e.g. the shift key was
            pressed).  XLookupString does all the work of  trans-
            lating  from  the event to an ASCII character.  Valid
            only for KeyPress and KeyRelease events.

       %B   The border_width field from the  event.   Valid  only
            for Configure events.
       %E   The  send_event  field from the event.  Valid for all
            event types.

       %K   The keysym corresponding to the event, substituted as
            a textual string.  Valid only for KeyPress and KeyRe-
            lease events.

       %N   The keysym corresponding to the event, substituted as
            a decimal number.  Valid only for KeyPress and KeyRe-
            lease events.

       %R   The root window identifier  from  the  event.   Valid
            only for events containing a root field.

       %S   The  subwindow window identifier from the event, for-
            matted as  a  hexadecimal  number.   Valid  only  for
            events containing a subwindow field.

       %T   The  type  field from the event.  Valid for all event
            types.

       %W   The path name of the window to which  the  event  was
            reported  (the  window  field from the event).  Valid
            for all event types.

       %X   The x_root field from the event.  If  a  virtual-root
            window  manager  is  being  used then the substituted
            value is the corresponding x-coordinate in  the  vir-
            tual  root.   Valid  only  for ButtonPress, ButtonRe-
            lease, KeyPress, KeyRelease, and Motion events.

       %Y   The y_root field from the event.  If  a  virtual-root
            window  manager  is  being  used then the substituted
            value is the corresponding y-coordinate in  the  vir-
            tual  root.   Valid  only  for ButtonPress, ButtonRe-
            lease, KeyPress, KeyRelease, and Motion events.

       The replacement string for a %-replacement is formatted as
       a  proper  Tcl  list  element.  This means that it will be
       surrounded with braces if it contains spaces,  or  special
       characters such as $ and { may be preceded by backslashes.
       This guarantees that the string will be passed through the
       Tcl  parser  when  the  binding script is evaluated.  Most
       replacements are numbers or well-defined strings  such  as
       Above;   for  these  replacements no special formatting is
       ever necessary.  The most common case  where  reformatting
       occurs is for the %A substitution.  For example, if script
       is
              insert %A
       and the character typed is an open  square  bracket,  then
       the script actually executed will be
              insert \[
       This  will  cause  the  insert  to  receive  the  original
       replacement string (open  square  bracket)  as  its  first
       argument.   If  the extra backslash hadn't been added, Tcl
       would not have been able to parse the script correctly.


MULTIPLE MATCHES
       It is possible for several bindings to  match  a  given  X
       event.   If  the  bindings  are  associated with different
       tag's, then each of the  bindings  will  be  executed,  in
       order.   By default, a binding for the widget will be exe-
       cuted first, followed by a class binding,  a  binding  for
       its  toplevel,  and  an all binding.  The bindtags command
       may be used to change this order for a  particular  window
       or to associate additional binding tags with the window.

       The continue and break commands may be used inside a bind-
       ing script to control the processing of matching  scripts.
       If continue is invoked, then the current binding script is
       terminated but Tk will continue processing binding scripts
       associated  with  other  tag's.   If  the break command is
       invoked within a binding script, then that  script  termi-
       nates  and no other scripts will be invoked for the event.

       If more than one binding matches a  particular  event  and
       they  have the same tag, then the most specific binding is
       chosen and its script is evaluated.  The  following  tests
       are  applied,  in  order,  to  determine  which of several
       matching sequences is more specific: (a) a longer sequence
       (in  terms  of  number of events matched) is more specific
       than a shorter sequence; (b) an event pattern that  speci-
       fies  a  specific  button or key is more specific than one
       that doesn't; (c) if the modifiers specified in  one  pat-
       tern  are  a  subset  of the modifiers in another pattern,
       then the pattern with more modifiers is more specific.  If
       the  matching  sequences contain more than one event, then
       tests (c)-(e) are applied in order from  the  most  recent
       event  to  the  least  recent  event in the sequences.  If
       these tests fail to determine  a  winner,  then  the  most
       recently registered sequence is the winner.

       If an X event does not match any of the existing bindings,
       then the event is ignored.  An unbound event is  not  con-
       sidered to be an error.


MULTI-EVENT SEQUENCES AND IGNORED EVENTS
       When  a sequence specified in a bind command contains more
       than one event pattern, then its script is executed  when-
       ever  the  recent  events (leading up to and including the
       current event) match the given sequence.  This means,  for
       example,  that  if  button  1  is  clicked  repeatedly the
       sequence <Double-ButtonPress-1>  will  match  each  button
       press but the first.  If extraneous events that would pre-
       vent a match occur in the middle of an event sequence then
       the extraneous events are ignored unless they are KeyPress
       or   ButtonPress   events.     For    example,    <Double-
       ButtonPress-1>  will match a sequence of presses of button
       1, even though there will  be  ButtonRelease  events  (and
       possibly  Motion  events)  between the ButtonPress events.
       Furthermore, a KeyPress event may be preceded by any  num-
       ber of other KeyPress events for modifier keys without the
       modifier keys preventing a match.  For example, the  event
       sequence  aB will match a press of the a key, a release of
       the a key, a press of the Shift key, and a press of the  b
       key:   the press of Shift is ignored because it is a modi-
       fier key.  Finally, if several Motion events  occur  in  a
       row,  only  the  last one is used for purposes of matching
       binding sequences.


ERRORS
       If an error occurs in executing the script for  a  binding
       then  the  tkerror  mechanism is used to report the error.
       The tkerror command will be executed at global level (out-
       side the context of any Tcl procedure).


SEE ALSO
       tkerror


KEYWORDS
       form, manual
