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 win-
       dow(s) identified by tag.  If script is prefixed with a ‘‘+’’, then  it
       is  appended  to  any  existing binding for sequence;  otherwise 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 speci-
       fied, 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 bind-
       tags 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 pat-
       terns, with optional white space between the patterns.  Each event pat-
       tern  may take one of three forms.  In the simplest case it is a single
       printing ASCII character, 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  pat-
       tern 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.

       The third form of pattern is used to specify a user-defined, named vir-
       tual event.  It has the following syntax:
              <<name>>
       The  entire  virtual event pattern is surrounded by double angle brack-
       ets.  Inside the angle brackets is the user-defined name of the virtual
       event.  Modifiers, such as Shift or Control, may not be combined with a
       virtual event to modify it.  Bindings on a virtual event may be created
       before the virtual event is defined, and if the definition of a virtual
       event changes dynamically, all windows bound to that virtual event will
       respond immediately to the new definition.

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                Quadruple

       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 binding 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 specified in the  bind-
       ing.   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 com-
       bination of modifiers may be present in the event.

       Meta and M refer to whichever of the M1 through M5 modifiers is associ-
       ated  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 modi-
       fiers,  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, Triple and Quadruple modifiers are a convenience for speci-
       fying double mouse clicks and other repeated events. They cause a  par-
       ticular  event pattern to be repeated 2, 3 or 4 times, and also place a
       time and space requirement on the sequence: for a sequence of events to
       match  a  Double,  Triple  or Quadruple 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  <But-
       ton-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.   The  type  field will also accept a couple non-
       standard X event types that were added to better support the  Macintosh
       and  Windows  platforms.  Below is a list of all the valid types; where
       two names appear together, they are synonyms.

              Activate            Destroy            Map
              ButtonPress, Button Enter              MapRequest
              ButtonRelease       Expose             Motion
              Circulate           FocusIn            MouseWheel
              CirculateRequest    FocusOut           Property
              Colormap            Gravity            Reparent
              Configure           KeyPress, Key      ResizeRequest
              ConfigureRequest    KeyRelease         Unmap
              Create              Leave              Visibility
              Deactivate


       Most of the above events have the same fields and behaviors  as  events
       in  the X Windowing system.  You can find more detailed descriptions of
       these events in any X window programming book.  A couple of the  events
       are  extensions to the X event system to support features unique to the
       Macintosh and Windows platforms.  We provide a little  more  detail  on
       these events here.  These include:

       Activate

       Deactivate
            These  two  events are sent to every sub-window of a toplevel when
            they change state.  In addition to the focus Window, the Macintosh
            platform  and  Windows platforms have a notion of an active window
            (which often has but is not required to have the focus).   On  the
            Macintosh,  widgets  in the active window have a different appear-
            ance than widgets in deactive windows.  The Activate event is sent
            to  all  the  sub-windows in a toplevel when it changes from being
            deactive to active.  Likewise, the Deactive event is sent when the
            window’s state changes from active to deactive.  There are no use-
            ful percent substitutions you would make  when  binding  to  these
            events.

       MouseWheel
            Some  mice  on the Windows platform support a mouse wheel which is
            used for scrolling documents without  using  the  scrollbars.   By
            rolling the wheel, the system will generate MouseWheel events that
            the application can use to scroll.  Like Key events the  event  is
            always  routed  to  the  window that currently has focus. When the
            event is received you can use the %D substitution to get the delta
            field  for  the  event which is a integer value of motion that the
            mouse wheel has moved.  The smallest value for  which  the  system
            will  report  is  defined  by the OS.  On Windows 95 & 98 machines
            this value is at least 120 before it is reported.  However, higher
            resolution  devices  may  be available in the future.  The sign of
            the value determines which direction your  widget  should  scroll.
            Positive values should scroll up and negative values should scroll
            down.

       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 partic-
       ular button will match;  if no button number is given, then an event on
       any button will match.  Note:  giving a specific button number is  dif-
       ferent  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  button  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  speci-
       fied  in  the  form of an X keysym.  Keysyms are textual specifications
       for particular keys on the keyboard; 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 neces-
       sary, 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 KeyPress.  For exam-
       ple, <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.  Command 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 generated by replacing each %,
       and  the  character  following  it,  with  information from the current
       event.  The replacement 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
       undefined.

       %%   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 hexadecimal number.
            Valid only for Configure events.

       %b   The number of the button that was pressed or released.  Valid only
            for ButtonPress and ButtonRelease 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 ConfigureRequest events, the string will be one of:

                   Above                   Opposite
                   Below                   None
                   BottomIf                TopIf

            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 for the Configure, Config-
            ureRequest, Create, ResizeRequest, and Expose events.

       %i   The  window  field  from  the  event, represented as a hexadecimal
            integer.

       %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,  NotifyUngrab,  or  NotifyWhileGrabbed.
            Valid only for Enter, FocusIn, FocusOut, and Leave 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 and Circu-
            lateRequest 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  Visi-
            bilityUnobscured,  VisibilityPartiallyObscured, and VisibilityFul-
            lyObscured 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 Configure, Config-
            ureRequest, Create, ResizeRequest, and Expose 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 UNICODE character corresponding to the  event,  or
            the  empty  string  if  the  event doesn’t correspond to a UNICODE
            character (e.g. the shift key was  pressed).  XmbLookupString  (or
            XLookupString  when  input  method support is turned off) does all
            the work of translating from the event  to  a  UNICODE  character.
            Valid only for KeyPress and KeyRelease events.

       %B   The  border_width field from the event.  Valid only for Configure,
            ConfigureRequest, and Create events.

       %D   This reports the delta value of a  MouseWheel  event.   The  delta
            value  represents  the  rotation  units  the  mouse wheel has been
            moved.  On Windows 95 & 98 systems  the  smallest  value  for  the
            delta is 120.  Future systems may support higher resolution values
            for the delta.  The sign of the value represents the direction the
            mouse wheel was scrolled.

       %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 KeyRelease events.

       %N   The keysym corresponding to the event, substituted  as  a  decimal
            number.  Valid only for KeyPress and KeyRelease 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,  formatted  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 virtual root.  Valid only for ButtonPress, But-
            tonRelease, 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 virtual root.  Valid only for ButtonPress,  But-
            tonRelease, 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  replace-
       ments  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 executed 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 binding script to
       control the processing of matching scripts.  If  continue  is  invoked,
       then the current binding script is terminated but Tk will continue pro-
       cessing binding scripts associated with other tag’s.  If the break com-
       mand  is  invoked  within a binding script, then that script terminates
       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) an event pat-
       tern that specifies a specific button or key is more specific than  one
       that  doesn’t;  (b)  a  longer  sequence  (in terms of number of events
       matched) is more specific than a shorter sequence; (c) if the modifiers
       specified  in one pattern are a subset of the modifiers in another pat-
       tern, then the pattern with more modifiers is  more  specific.   (d)  a
       virtual  event whose physical pattern matches the sequence is less spe-
       cific than the same physical pattern that is not associated with a vir-
       tual  event.   (e)  given  a  sequence that matches two or more virtual
       events, one of the virtual events will be  chosen,  but  the  order  is
       undefined.

       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 win-
       ner, then the most recently registered sequence is the winner.

       If there are two (or more) virtual events that are  both  triggered  by
       the  same  sequence,  and both of those virtual events are bound to the
       same window tag, then only one of the virtual events will be triggered,
       and it will be picked at random:
              event add <<Paste>> <Control-y>
              event add <<Paste>> <Button-2>
              event add <<Scroll>> <Button-2>
              bind Entry <<Paste>> {puts Paste}
              bind Entry <<Scroll>> {puts Scroll}
       If the user types Control-y, the <<Paste>> binding will be invoked, but
       if the user presses button 2 then one of either the  <<Paste>>  or  the
       <<Scroll>> bindings will be invoked, but exactly which one gets invoked
       is undefined.

       If an X event does not match any of the  existing  bindings,  then  the
       event is ignored.  An unbound event is not considered 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 whenever 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 repeat-
       edly  the  sequence <Double-ButtonPress-1> will match each button press
       but the first.  If extraneous events that would prevent 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 number 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 modifier  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 bger-
       ror mechanism is used to report the error.  The bgerror command will be
       executed at global level (outside the context of any Tcl procedure).


SEE ALSO
       bgerror, keysyms


KEYWORDS
