Provided by: tk8.6-doc_8.6.10-1_all bug

NAME

       bind - Arrange for X events to invoke Tcl scripts

SYNOPSIS

       bind tag ?sequence? ?+??script?
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INTRODUCTION

       The  bind  command  associates  Tcl  scripts  with  X  events.  If all three arguments are
       specified, bind will arrange for script (a Tcl script called the “binding script”)  to  be
       evaluated  whenever  the  event(s)  given by sequence occur in the window(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 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 patterns.  Each event pattern 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 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.

       The third form of pattern is used to specify a user-defined, named virtual event.  It  has
       the following syntax:
              <<name>>
       The entire virtual event pattern is surrounded by double angle brackets.  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.

       Some widgets (e.g. menu and text) issue  virtual  events  when  their  internal  state  is
       updated in some ways.  Please see the manual page for each widget for details.

   MODIFIERS
       Modifiers consist of any of the following values:

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

       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 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 modifiers 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, Triple and Quadruple modifiers are a convenience for specifying  double  mouse
       clicks  and other repeated events. They cause a particular 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  <Button-1><Button-1>  with the extra time and space
       requirement.

       The Command and Option modifiers are equivalents of Mod1 resp. Mod2,  they  correspond  to
       Macintosh-specific modifier keys.

       The  Extended modifier is, at present, specific to Windows.  It appears on events that are
       associated with the keys on the “extended keyboard”.  On a US keyboard, the extended  keys
       include  the  Alt  and  Control  keys at the right of the keyboard, the cursor keys in the
       cluster to the left of the numeric pad, the NumLock key, the Break  key,  the  PrintScreen
       key, and the / and Enter keys in the numeric keypad.

   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 appearance 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 useful
            percent substitutions you would make when binding to these events.

       MouseWheel
            Many  contemporary  mice 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 describing how the mouse wheel has moved.  The smallest value for which
            the  system  will report is defined by the OS. The sign of the value determines which
            direction your widget should scroll.  Positive values should scroll up  and  negative
            values should scroll down.

       KeyPress, KeyRelease
            The  KeyPress  and  KeyRelease  events  are  generated  whenever  a key is pressed or
            released.  KeyPress and KeyRelease events are sent to the window which currently  has
            the keyboard focus.

       ButtonPress, ButtonRelease, Motion
            The  ButtonPress  and  ButtonRelease  events  are  generated when the user presses or
            releases a mouse button.  Motion events are generated whenever the pointer is  moved.
            ButtonPress,  ButtonRelease,  and  Motion  events  are  normally  sent  to the window
            containing the pointer.

            When a mouse button is pressed,  the  window  containing  the  pointer  automatically
            obtains  a temporary pointer grab.  Subsequent ButtonPress, ButtonRelease, and Motion
            events will be sent to that window, regardless of which window contains the  pointer,
            until all buttons have been released.

       Configure
            A  Configure  event  is sent to a window whenever its size, position, or border width
            changes, and sometimes when it has changed position in the stacking order.

       Map, Unmap
            The Map and Unmap events are  generated  whenever  the  mapping  state  of  a  window
            changes.

            Windows are created in the unmapped state.  Top-level windows become mapped when they
            transition to the normal state, and are unmapped in the withdrawn and iconic  states.
            Other  windows become mapped when they are placed under control of a geometry manager
            (for example pack or grid).

            A window is viewable only if it and all of  its  ancestors  are  mapped.   Note  that
            geometry  managers  typically  do  not map their children until they have been mapped
            themselves, and unmap all children when they become unmapped; hence  in  Tk  Map  and
            Unmap events indicate whether or not a window is viewable.

       Visibility
            A  window  is  said to be obscured when another window above it in the stacking order
            fully or partially overlaps it.  Visibility events are generated whenever a  window's
            obscurity state changes; the state field (%s) specifies the new state.

       Expose
            An  Expose event is generated whenever all or part of a window should be redrawn (for
            example, when a window is first mapped or if it becomes unobscured).  It is  normally
            not  necessary for client applications to handle Expose events, since Tk handles them
            internally.

       Destroy
            A Destroy event is delivered to a window when it is destroyed.

            When the Destroy event is delivered to a widget, it is in a  “half-dead”  state:  the
            widget still exists, but most operations on it will fail.

       FocusIn, FocusOut
            The FocusIn and FocusOut events are generated whenever the keyboard focus changes.  A
            FocusOut event is sent to the old focus window, and a FocusIn event is  sent  to  the
            new one.

            In  addition, if the old and new focus windows do not share a common parent, “virtual
            crossing” focus events are sent to the intermediate windows in the hierarchy.  Thus a
            FocusIn event indicates that the target window or one of its descendants has acquired
            the focus, and a FocusOut event indicates that the focus has been changed to a window
            outside the target window's hierarchy.

            The keyboard focus may be changed explicitly by a call to focus, or implicitly by the
            window manager.

       Enter, Leave
            An Enter event is sent to a window when the pointer enters that window, and  a  Leave
            event is sent when the pointer leaves it.

            If  there  is  a pointer grab in effect, Enter and Leave events are only delivered to
            the window owning the grab.

            In addition, when the pointer moves between two windows,  Enter  and  Leave  “virtual
            crossing” events are sent to intermediate windows in the hierarchy in the same manner
            as for FocusIn and FocusOut events.

       Property
            A Property event is sent to a window whenever an X property belonging to that  window
            is changed or deleted.  Property events are not normally delivered to Tk applications
            as they are handled by the Tk core.

       Colormap
            A Colormap event is generated whenever the colormap associated with a window has been
            changed, installed, or uninstalled.

            Widgets  may  be  assigned  a  private colormap by specifying a -colormap option; the
            window manager is responsible for installing and uninstalling colormaps as necessary.

            Note that Tk provides no useful details for this event type.

       MapRequest, CirculateRequest, ResizeRequest, ConfigureRequest, Create
            These events are not normally delivered to Tk applications.  They  are  included  for
            completeness,  to make it possible to write X11 window managers in Tk.  (These events
            are only delivered when a client has selected SubstructureRedirectMask on  a  window;
            the Tk core does not use this mask.)

       Gravity, Reparent, Circulate
            The  events Gravity and Reparent are not normally delivered to Tk applications.  They
            are included for completeness.

            A Circulate event indicates that the window has moved to the top or to the bottom  of
            the  stacking  order  as  a result of an XCirculateSubwindows protocol request.  Note
            that the stacking order may be changed for other reasons  which  do  not  generate  a
            Circulate  event,  and  that Tk does not use XCirculateSubwindows() internally.  This
            event type is included only for completeness; there  is  no  reliable  way  to  track
            changes to a window's position in the stacking order.

   EVENT DETAILS
       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  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 specified 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
       (e.g.  “Shift_L” is the keysym 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
       KeyPress.  For example, <Control-comma> is equivalent to <Control-KeyPress-comma>.

BINDING SCRIPTS AND SUBSTITUTIONS

       The  script  argument  to bind is a Tcl script, called the “binding 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.  Indicates the  sibling  window  immediately  below  the  receiving
            window in the stacking order, or 0 if the receiving window is at the bottom.

       %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.  Indicates that  there
            are count pending Expose events which have not yet been delivered to the window.

       %d   The  detail  or  user_data  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  virtual  events,  the  string  will be whatever value is stored in the user_data
            field when the event was created (typically with event generate), or the empty string
            if  the  field  is  NULL.   Virtual events corresponding to key sequence presses (see
            event add for details) set the user_data to NULL.  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.  1
            if the receiving window is the focus window or a descendant of the  focus  window,  0
            otherwise.

       %h   The  height field from the event.  Valid for the Configure, ConfigureRequest, Create,
            ResizeRequest, and Expose events.  Indicates the  new  or  requested  height  of  the
            window.

       %i   The window field from the event, represented as a hexadecimal integer.  Valid for all
            event types.

       %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 CirculateRequest 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 VisibilityUnobscured, VisibilityPartiallyObscured, and
            VisibilityFullyObscured is substituted.  For Property events, substituted with either
            the string NewValue (indicating that the property has been created  or  modified)  or
            Delete (indicating that the property has been removed).

       %t   The  time  field  from the event.  This is the X server timestamp (typically the time
            since the last server reset) in milliseconds, when the  event  occurred.   Valid  for
            most events.

       %w   The  width field from the event.  Indicates the new or requested width of the window.
            Valid only for Configure, ConfigureRequest, Create, ResizeRequest, and Expose events.

       %x, %y
            The x and y fields from the event.  For ButtonPress, ButtonRelease, Motion, KeyPress,
            KeyRelease,  and  MouseWheel  events,  %x  and  %y indicate the position of the mouse
            pointer relative to the receiving window.  For Enter and Leave events,  the  position
            where  the  mouse  pointer crossed the window, relative to the receiving window.  For
            Configure and Create requests, the x and y coordinates of the window relative to  its
            parent window.

       %A   Substitutes  the UNICODE character corresponding to the event, or the empty string if
            the event does not 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. 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.   0  indicates  that
            this  is  a  “normal”  event, 1 indicates that it is a “synthetic” event generated by
            SendEvent.

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

       %M   The  number of script-based binding patterns matched so far for the event.  Valid for
            all event types.

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

       %P   The name of the property being updated or deleted (which may be converted to an XAtom
            using winfo atom.) Valid only for Property 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, %Y
            The  x_root  and   y_root fields from the event.  If a virtual-root window manager is
            being used then the substituted values are  the  corresponding  x-coordinate  and  y-
            coordinate  in  the  virtual root.  Valid only for ButtonPress, ButtonRelease, Enter,
            KeyPress, KeyRelease, Leave and Motion events.  Same meaning as  %x  and  %y,  except
            relative to the (virtual) root window.

       The  replacement  string  for  a  %-replacement is formatted as a proper Tcl list element.
       This means that 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 had not 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 within a binding script, then this
       binding  script,  including  all  other  “+”  appended  scripts, 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 terminates and no other scripts will be
       invoked for the event.

       Within a script called from the binding script, return -code ok may be  used  to  continue
       processing  (including  “+”  appended  scripts), or return -code break may be used to stop
       processing all other binding scripts.

       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 pattern that specifies a specific button or key  is  more  specific
                     than one that does not;

              (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 pattern, then the pattern with more modifiers is more specific;

              (d)    a virtual event whose physical pattern matches the sequence is less specific
                     than the same physical pattern that is not associated with a virtual 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  winner,  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
       repeatedly 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  bgerror  mechanism  is
       used  to  report the error.  The bgerror command will be executed at global level (outside
       the context of any Tcl procedure).

EXAMPLES

       Arrange for a string describing the motion of the mouse to be printed out when  the  mouse
       is double-clicked:
              bind . <Double-1> {
                  puts "hi from (%x,%y)"
              }

       A little GUI that displays what the keysym name of the last key pressed is:
              set keysym "Press any key"
              pack [label .l -textvariable keysym -padx 2m -pady 1m]
              bind . <Key> {
                  set keysym "You pressed %K"
              }

SEE ALSO

       bgerror(3tcl), bindtags(3tk), event(3tk), focus(3tk), grab(3tk), keysyms(3tk)

KEYWORDS

       binding, event