1bind(n)                      Tk Built-In Commands                      bind(n)
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6

NAME

8       bind - Arrange for X events to invoke Tcl scripts
9

SYNOPSIS

11       bind tag ?sequence? ?+??script?
12_________________________________________________________________
13

INTRODUCTION

15       The  bind  command  associates Tcl scripts with X events.  If all three
16       arguments are specified, bind will arrange for script (a Tcl script) to
17       be  evaluated whenever the event(s) given by sequence occur in the win‐
18       dow(s) identified by tag.  If script is prefixed with a “+”, then it is
19       appended  to  any  existing  binding  for  sequence;   otherwise script
20       replaces any existing binding.  If script is an empty string  then  the
21       current  binding  for  sequence is destroyed, leaving sequence unbound.
22       In all of the cases where a script argument is provided,  bind  returns
23       an empty string.
24
25       If  sequence  is  specified without a script, then the script currently
26       bound to sequence is returned, or an empty string is returned if  there
27       is  no  binding for sequence.  If neither sequence nor script is speci‐
28       fied, then the return value is  a  list  whose  elements  are  all  the
29       sequences for which there exist bindings for tag.
30
31       The tag argument determines which window(s) the binding applies to.  If
32       tag begins with a dot, as in .a.b.c, then it must be the path name  for
33       a  window; otherwise it may be an arbitrary string.  Each window has an
34       associated list of tags, and a binding applies to a  particular  window
35       if its tag is among those specified for the window.  Although the bind‐
36       tags command may be used to assign an arbitrary set of binding tags  to
37       a window, the default binding tags provide the following behavior:
38
39       ·  If  a  tag  is the name of an internal window the binding applies to
40          that window.
41
42       ·  If the tag is the name of a toplevel window the binding  applies  to
43          the toplevel window and all its internal windows.
44
45       ·  If  the  tag  is the name of a class of widgets, such as Button, the
46          binding applies to all widgets in that class;
47
48       ·  If tag has the value all, the binding applies to all windows in  the
49          application.
50

EVENT PATTERNS

52       The  sequence  argument  specifies a sequence of one or more event pat‐
53       terns, with optional white space between the patterns.  Each event pat‐
54       tern  may take one of three forms.  In the simplest case it is a single
55       printing ASCII character, such as a or [.  The character may not  be  a
56       space  character  or  the  character <.  This form of pattern matches a
57       KeyPress event for the particular character.  The second form  of  pat‐
58       tern is longer but more general.  It has the following syntax:
59              <modifier-modifier-type-detail>
60       The  entire  event pattern is surrounded by angle brackets.  Inside the
61       angle brackets are zero or more modifiers, an event type, and an  extra
62       piece  of  information  (detail)  identifying  a  particular  button or
63       keysym.  Any of the fields may be omitted, as long as at least  one  of
64       type  and  detail  is  present.   The fields must be separated by white
65       space or dashes.
66
67       The third form of pattern is used to specify a user-defined, named vir‐
68       tual event.  It has the following syntax:
69              <<name>>
70       The  entire  virtual event pattern is surrounded by double angle brack‐
71       ets.  Inside the angle brackets is the user-defined name of the virtual
72       event.  Modifiers, such as Shift or Control, may not be combined with a
73       virtual event to modify it.  Bindings on a virtual event may be created
74       before the virtual event is defined, and if the definition of a virtual
75       event changes dynamically, all windows bound to that virtual event will
76       respond immediately to the new definition.
77
78       Some  widgets  (e.g.  menu  and  text)  issue virtual events when their
79       internal state is updated in some ways.  Please see the manual page for
80       each widget for details.
81
82   MODIFIERS
83       Modifiers    consist   of   any   of   the   following   values:   Con‐
84       trol                 Mod1,  M1,  Command  Alt                     Mod2,
85       M2,           Option          Shift                   Mod3,          M3
86       Lock                    Mod4, M4 Extended                Mod5, M5  But‐
87       ton1,  B1           Meta,  M  Button2,  B2             Double  Button3,
88       B3             Triple  Button4,  B4             Quadruple  Button5,  B5
89       Where  more  than  one value is listed, separated by commas, the values
90       are equivalent.  Most of the modifiers have  the  obvious  X  meanings.
91       For example, Button1 requires that button 1 be depressed when the event
92       occurs.  For a binding to match a given event,  the  modifiers  in  the
93       event  must  include  all  of those specified in the event pattern.  An
94       event may also contain additional modifiers not specified in the  bind‐
95       ing.   For  example, if button 1 is pressed while the shift and control
96       keys are down, the pattern <Control-Button-1> will match the event, but
97       <Mod1-Button-1> will not.  If no modifiers are specified, then any com‐
98       bination of modifiers may be present in the event.
99
100       Meta and M refer to whichever of the M1 through M5 modifiers is associ‐
101       ated  with the Meta key(s) on the keyboard (keysyms Meta_R and Meta_L).
102       If there are no Meta keys, or if they are not associated with any modi‐
103       fiers,  then  Meta and M will not match any events.  Similarly, the Alt
104       modifier refers to whichever modifier is associated with the alt key(s)
105       on the keyboard (keysyms Alt_L and Alt_R).
106
107       The Double, Triple and Quadruple modifiers are a convenience for speci‐
108       fying double mouse clicks and other repeated events. They cause a  par‐
109       ticular  event pattern to be repeated 2, 3 or 4 times, and also place a
110       time and space requirement on the sequence: for a sequence of events to
111       match  a  Double,  Triple  or Quadruple pattern, all of the events must
112       occur close together in time and without substantial  mouse  motion  in
113       between.    For  example,  <Double-Button-1>  is  equivalent  to  <But‐
114       ton-1><Button-1> with the extra time and space requirement.
115
116       The Command and Option modifiers are equivalents of  Mod1  resp.  Mod2,
117       they correspond to Macintosh-specific modifier keys.
118
119       The  Extended modifier is, at present, specific to Windows.  It appears │
120       on events that are associated with the keys on the “extended keyboard”. │
121       On a US keyboard, the extended keys include the Alt and Control keys at │
122       the right of the keyboard, the cursor keys in the cluster to  the  left │
123       of  the  numeric  pad,  the NumLock key, the Break key, the PrintScreen 
124       key, and the / and Enter keys in the numeric keypad.
125
126   EVENT TYPES
127       The type field may be any of the standard X event  types,  with  a  few
128       extra  abbreviations.   The  type  field will also accept a couple non-
129       standard X event types that were added to better support the  Macintosh
130       and  Windows  platforms.  Below is a list of all the valid types; where
131       two   names   appear    together,    they    are    synonyms.     Acti‐
132       vate              Destroy         Map         ButtonPress,         But‐
133       ton   Enter           MapRequest                              ButtonRe‐
134       lease         Expose          Motion                             Circu‐
135       late             FocusIn         MouseWheel CirculateRequest      Focu‐
136       sOut        Property     Colormap              Gravity         Reparent
137       Configure             KeyPress,       KeyResizeRequest        Configur‐
138       eRequest      KeyRelease      Unmap                                Cre‐
139       ate                Leave           Visibility Deactivate  Most  of  the
140       above events have the same fields and behaviors as events in the X Win‐
141       dowing system.  You can find more detailed descriptions of these events
142       in  any  X  window programming book.  A couple of the events are exten‐
143       sions to the X event system to support features unique to the Macintosh
144       and Windows platforms.  We provide a little more detail on these events
145       here.  These include:
146
147       Activate, Deactivate
148            These two events are sent to every sub-window of a  toplevel  when
149            they change state.  In addition to the focus Window, the Macintosh
150            platform and Windows platforms have a notion of an  active  window
151            (which  often  has but is not required to have the focus).  On the
152            Macintosh, widgets in the active window have a  different  appear‐
153            ance than widgets in deactive windows.  The Activate event is sent
154            to all the sub-windows in a toplevel when it  changes  from  being
155            deactive to active.  Likewise, the Deactive event is sent when the
156            window's state changes from active to deactive.  There are no use‐
157            ful  percent  substitutions  you  would make when binding to these
158            events.
159
160       MouseWheel
161            Many contemporary mice support a mouse wheel, which  is  used  for
162            scrolling  documents without using the scrollbars.  By rolling the
163            wheel, the system will generate MouseWheel events that the  appli‐
164            cation  can  use  to  scroll.  Like Key events the event is always
165            routed to the window that currently has focus. When the  event  is
166            received  you  can  use the %D substitution to get the delta field
167            for the event, which is a integer value describing how  the  mouse
168            wheel  has  moved.   The  smallest value for which the system will
169            report is defined by the OS.  On Windows 95  &  98  machines  this
170            value is at least 120 before it is reported.  However, higher res‐
171            olution devices may be available in the future.  The sign  of  the
172            value determines which direction your widget should scroll.  Posi‐
173            tive values should scroll up and  negative  values  should  scroll
174            down.
175
176       KeyPress, KeyRelease
177            The KeyPress and KeyRelease events are generated whenever a key is
178            pressed or released.  KeyPress and KeyRelease events are  sent  to
179            the window which currently has the keyboard focus.
180
181       ButtonPress, ButtonRelease, Motion
182            The  ButtonPress  and  ButtonRelease events are generated when the
183            user presses or releases a mouse button.  Motion events are gener‐
184            ated  whenever  the pointer is moved.  ButtonPress, ButtonRelease,
185            and Motion events are normally sent to the window  containing  the
186            pointer.
187
188            When  a mouse button is pressed, the window containing the pointer
189            automatically obtains a temporary pointer grab.   Subsequent  But‐
190            tonPress,  ButtonRelease,  and  Motion events will be sent to that
191            window, regardless of which window contains the pointer, until all
192            buttons have been released.
193
194       Configure
195            A Configure event is sent to a window whenever its size, position,
196            or border width changes, and sometimes when it has  changed  posi‐
197            tion in the stacking order.
198
199       Map, Unmap
200            The  Map and Unmap events are generated whenever the mapping state
201            of a window changes.
202
203            Windows are created in  the  unmapped  state.   Top-level  windows
204            become  mapped  when  they transition to the normal state, and are
205            unmapped in the withdrawn and iconic states.  Other windows become
206            mapped  when  they  are placed under control of a geometry manager
207            (for example pack or grid).
208
209            A window is viewable only if it  and  all  of  its  ancestors  are
210            mapped.   Note  that  geometry managers typically do not map their
211            children until they have been mapped  themselves,  and  unmap  all
212            children  when  they  become  unmapped;  hence in Tk Map and Unmap
213            events indicate whether or not a window is viewable.
214
215       Visibility
216            A window is said to be obscured when another window  above  it  in
217            the  stacking  order  fully  or partially overlaps it.  Visibility
218            events are generated whenever a window's obscurity state  changes;
219            the state field (%s) specifies the new state.
220
221       Expose
222            An  Expose  event  is  generated  whenever all or part of a window
223            should be redrawn (for example, when a window is first  mapped  or
224            if  it  becomes  unobscured).   It  is  normally not necessary for
225            client applications to handle Expose events, since Tk handles them
226            internally.
227
228       Destroy
229            A Destroy event is delivered to a window when it is destroyed.
230
231            When the Destroy event is delivered to a widget, it is in a “half-
232            dead” state: the widget still exists, but most  operations  on  it
233            will fail.
234
235       FocusIn, FocusOut
236            The  FocusIn  and  FocusOut events are generated whenever the key‐
237            board focus changes.  A FocusOut event is sent to  the  old  focus
238            window, and a FocusIn event is sent to the new one.
239
240            In  addition, if the old and new focus windows do not share a com‐
241            mon parent, “virtual crossing” focus events are sent to the inter‐
242            mediate  windows in the hierarchy.  Thus a FocusIn event indicates
243            that the target window or one of its descendants has acquired  the
244            focus,  and  a  FocusOut  event  indicates that the focus has been
245            changed to a window outside the target window's hierarchy.
246
247            The keyboard focus may be changed explicitly by a call  to  focus,
248            or implicitly by the window manager.
249
250       Enter, Leave
251            An  Enter  event  is sent to a window when the pointer enters that
252            window, and a Leave event is sent when the pointer leaves it.
253
254            If there is a pointer grab in effect, Enter and Leave  events  are
255            only delivered to the window owning the grab.
256
257            In addition, when the pointer moves between two windows, Enter and
258            Leave “virtual crossing” events are sent to  intermediate  windows
259            in  the  hierarchy  in the same manner as for FocusIn and FocusOut
260            events.
261
262       Property
263            A Property event is sent  to  a  window  whenever  an  X  property
264            belonging  to  that window is changed or deleted.  Property events
265            are not normally delivered to Tk applications as they are  handled
266            by the Tk core.
267
268       Colormap
269            A  Colormap  event  is  generated whenever the colormap associated
270            with a window has been changed, installed, or uninstalled.
271
272            Widgets may be assigned a private colormap by specifying  a  -col‐
273            ormap option; the window manager is responsible for installing and
274            uninstalling colormaps as necessary.
275
276            Note that Tk provides no useful details for this event type.
277
278       MapRequest, CirculateRequest, ResizeRequest, ConfigureRequest, Create
279            These events are not normally delivered to Tk applications.   They
280            are  included  for  completeness, to make it possible to write X11
281            window managers in Tk.  (These events are only  delivered  when  a
282            client  has  selected SubstructureRedirectMask on a window; the Tk
283            core does not use this mask.)
284
285       Gravity, Reparent, Circulate
286            The events Gravity and Reparent are not normally delivered  to  Tk
287            applications.  They are included for completeness.
288
289            A  Circulate  event indicates that the window has moved to the top
290            or to the bottom of the stacking order as a result of  an  XCircu‐
291            lateSubwindows protocol request.  Note that the stacking order may
292            be changed for other reasons which do  not  generate  a  Circulate
293            event, and that Tk does not use XCirculateSubwindows() internally.
294            This event type is included only for  completeness;  there  is  no
295            reliable way to track changes to a window's position in the stack‐
296            ing order.
297
298   EVENT DETAILS
299       The last part of a long event specification is detail.  In the case  of
300       a  ButtonPress  or  ButtonRelease  event,  it is the number of a button
301       (1-5).  If a button number is given, then only an event on that partic‐
302       ular button will match;  if no button number is given, then an event on
303       any button will match.  Note:  giving a specific button number is  dif‐
304       ferent  than specifying a button modifier; in the first case, it refers
305       to a button being pressed or released, while in the second it refers to
306       some  other  button  that  is already depressed when the matching event
307       occurs.  If a button number is given then type may be omitted:  if will
308       default  to  ButtonPress.  For example, the specifier <1> is equivalent
309       to <ButtonPress-1>.
310
311       If the event type is KeyPress or KeyRelease, then detail may be  speci‐
312       fied  in  the  form of an X keysym.  Keysyms are textual specifications
313       for particular keys on the keyboard; they include all the  alphanumeric
314       ASCII characters (e.g.  “a” is the keysym for the ASCII character “a”),
315       plus descriptions for non-alphanumeric characters (“comma”is the keysym
316       for  the comma character), plus descriptions for all the non-ASCII keys
317       on the keyboard (e.g.  “Shift_L” is the keysym for the left shift  key,
318       and  “F1”  is  the  keysym for the F1 function key, if it exists).  The
319       complete list of keysyms is not presented here;   it  is  available  in
320       other  X  documentation  and may vary from system to system.  If neces‐
321       sary, you can use the %K notation described  below  to  print  out  the
322       keysym  name  for  a particular key.  If a keysym detail is given, then
323       the type field may be omitted;  it will default to KeyPress.  For exam‐
324       ple, <Control-comma> is equivalent to <Control-KeyPress-comma>.
325

BINDING SCRIPTS AND SUBSTITUTIONS

327       The  script  argument  to  bind is a Tcl script, which will be executed
328       whenever the given event sequence occurs.  Command will be executed  in
329       the same interpreter that the bind command was executed in, and it will
330       run at global level (only global variables  will  be  accessible).   If
331       script  contains any % characters, then the script will not be executed
332       directly.  Instead, a new script will be generated by replacing each %,
333       and  the  character  following  it,  with  information from the current
334       event.  The replacement depends on the character following  the  %,  as
335       defined in the list below.  Unless otherwise indicated, the replacement
336       string is the decimal value of the given field from the current  event.
337       Some  of  the substitutions are only valid for certain types of events;
338       if they are used for other types of events  the  value  substituted  is
339       undefined.
340
341       %%   Replaced with a single percent.
342
343       %#   The number of the last client request processed by the server (the
344            serial field from the event).  Valid for all event types.
345
346       %a   The above field from the event, formatted as a hexadecimal number.
347            Valid  only  for  Configure  events.  Indicates the sibling window
348            immediately below the receiving window in the stacking order, or 0
349            if the receiving window is at the bottom.
350
351       %b   The number of the button that was pressed or released.  Valid only
352            for ButtonPress and ButtonRelease events.
353
354       %c   The count field from the event.  Valid  only  for  Expose  events.
355            Indicates  that  there  are count pending Expose events which have
356            not yet been delivered to the window.
357
358       %d   The detail or user_data field from the event.  The %d is  replaced │
359            by  a  string  identifying the detail.  For Enter, Leave, FocusIn,
360            and FocusOut events, the string will be one of the following:
361            NotifyAncestor          NotifyNonlinearVirtual       NotifyDetail‐
362            None        NotifyPointer   NotifyInferior          NotifyPointer‐
363            Root  NotifyNonlinear         NotifyVirtual  For  ConfigureRequest
364            events,  the  string will be one of: Above                   Oppo‐
365            site  Below                   None   BottomIf                TopIf 
366            For virtual events, the string will be whatever value is stored in │
367            the user_data field when the event  was  created  (typically  with │
368            event  generate),  or the empty string if the field is NULL.  Vir‐ │
369            tual events corresponding to key sequence presses (see  event  add 
370            for  details)  set  the  user_data to NULL.  For events other than
371            these, the substituted string is undefined.
372
373       %f   The focus field from the event (0 or 1).  Valid only for Enter and
374            Leave  events.  1 if the receiving window is the focus window or a
375            descendant of the focus window, 0 otherwise.
376
377       %h   The height field from the event.  Valid for the Configure, Config‐
378            ureRequest,  Create,  ResizeRequest, and Expose events.  Indicates
379            the new or requested height of the window.
380
381       %i   The window field from the  event,  represented  as  a  hexadecimal
382            integer.  Valid for all event types.
383
384       %k   The  keycode  field  from  the event.  Valid only for KeyPress and
385            KeyRelease events.
386
387       %m   The mode field from the event.  The substituted string is  one  of
388            NotifyNormal,  NotifyGrab,  NotifyUngrab,  or  NotifyWhileGrabbed.
389            Valid only for Enter, FocusIn, FocusOut, and Leave events.
390
391       %o   The override_redirect field from the event.  Valid only  for  Map,
392            Reparent, and Configure events.
393
394       %p   The  place field from the event, substituted as one of the strings
395            PlaceOnTop or PlaceOnBottom.  Valid only for Circulate and  Circu‐
396            lateRequest events.
397
398       %s   The  state  field from the event.  For ButtonPress, ButtonRelease,
399            Enter, KeyPress, KeyRelease, Leave, and Motion events,  a  decimal
400            string  is  substituted.  For Visibility, one of the strings Visi‐
401            bilityUnobscured, VisibilityPartiallyObscured, and  VisibilityFul‐
402            lyObscured  is substituted.  For Property events, substituted with
403            either the string NewValue (indicating that the property has  been
404            created  or  modified) or Delete (indicating that the property has
405            been removed).
406
407       %t   The time field from the event.  This is  the  X  server  timestamp
408            (typically  the time since the last server reset) in milliseconds,
409            when the event occurred.  Valid for most events.
410
411       %w   The width field from the event.  Indicates the  new  or  requested
412            width  of the window.  Valid only for Configure, ConfigureRequest,
413            Create, ResizeRequest, and Expose events.
414
415       %x, %y
416            The x and y fields from the  event.   For  ButtonPress,  ButtonRe‐
417            lease, Motion, KeyPress, KeyRelease, and MouseWheel events, %x and
418            %y indicate the position of the  mouse  pointer  relative  to  the
419            receiving  window.  For Enter and Leave events, the position where
420            the mouse pointer crossed the window, relative  to  the  receiving
421            window.   For  Configure  and Create requests, the x and y coordi‐
422            nates of the window relative to its parent window.
423
424       %A   Substitutes the UNICODE character corresponding to the  event,  or
425            the  empty  string  if  the event does not correspond to a UNICODE
426            character (e.g. the shift key was  pressed).  XmbLookupString  (or
427            XLookupString  when  input  method support is turned off) does all
428            the work of translating from the event  to  a  UNICODE  character.
429            Valid only for KeyPress and KeyRelease events.
430
431       %B   The  border_width field from the event.  Valid only for Configure,
432            ConfigureRequest, and Create events.
433
434       %D   This reports the delta value of a  MouseWheel  event.   The  delta
435            value  represents  the  rotation  units  the  mouse wheel has been
436            moved.  On Windows 95 & 98 systems  the  smallest  value  for  the
437            delta is 120.  Future systems may support higher resolution values
438            for the delta.  The sign of the value represents the direction the
439            mouse wheel was scrolled.
440
441       %E   The  send_event  field from the event.  Valid for all event types.
442            0 indicates that this is a “normal” event, 1 indicates that it  is
443            a “synthetic” event generated by SendEvent.
444
445       %K   The  keysym  corresponding  to the event, substituted as a textual
446            string.  Valid only for KeyPress and KeyRelease events.
447
448       %N   The keysym corresponding to the event, substituted  as  a  decimal
449            number.  Valid only for KeyPress and KeyRelease events.
450
451       %P   The  name  of  the property being updated or deleted (which may be
452            converted to an XAtom using winfo atom.) Valid only  for  Property
453            events.
454
455       %R   The  root window identifier from the event.  Valid only for events
456            containing a root field.
457
458       %S   The subwindow window identifier from the  event,  formatted  as  a
459            hexadecimal  number.  Valid only for events containing a subwindow
460            field.
461
462       %T   The type field from the event.  Valid for all event types.
463
464       %W   The path name of the window to which the event was  reported  (the
465            window field from the event).  Valid for all event types.
466
467       %X, %Y
468            The  x_root  and  y_root fields from the event.  If a virtual-root
469            window manager is being used then the substituted values  are  the
470            corresponding  x-coordinate  and y-coordinate in the virtual root.
471            Valid only for ButtonPress, ButtonRelease,  KeyPress,  KeyRelease,
472            and  Motion events.  Same meaning as %x and %y, except relative to
473            the (virtual) root window.
474
475       The replacement string for a %-replacement is formatted as a proper Tcl
476       list  element.   This means that spaces or special characters such as $
477       and { may be preceded by backslashes.  This guarantees that the  string
478       will be passed through the Tcl parser when the binding script is evalu‐
479       ated.  Most replacements are numbers or well-defined  strings  such  as
480       Above;  for these replacements no special formatting is ever necessary.
481       The most common case where reformatting occurs is for the %A  substitu‐
482       tion.  For example, if script is
483              insert %A
484       and  the  character  typed  is  an open square bracket, then the script
485       actually executed will be
486              insert \[
487       This will cause the insert to receive the original  replacement  string
488       (open  square  bracket)  as its first argument.  If the extra backslash
489       had not been added, Tcl would not have been able to  parse  the  script
490       correctly.
491

MULTIPLE MATCHES

493       It  is  possible for several bindings to match a given X event.  If the
494       bindings are associated with different tag's, then each of the bindings
495       will  be executed, in order.  By default, a binding for the widget will
496       be executed first, followed by a  class  binding,  a  binding  for  its
497       toplevel,  and  an  all  binding.   The bindtags command may be used to
498       change this order for a particular window or  to  associate  additional
499       binding tags with the window.
500
501       The  continue and break commands may be used inside a binding script to
502       control the processing of matching scripts.  If  continue  is  invoked,
503       then the current binding script is terminated but Tk will continue pro‐
504       cessing binding scripts associated with other tag's.  If the break com‐
505       mand  is  invoked  within a binding script, then that script terminates
506       and no other scripts will be invoked for the event.
507
508       If more than one binding matches a particular event and they  have  the
509       same  tag,  then  the most specific binding is chosen and its script is
510       evaluated.  The following tests are applied,  in  order,  to  determine
511       which of several matching sequences is more specific:
512
513              (a)    an  event pattern that specifies a specific button or key
514                     is more specific than one that does not;
515
516              (b)    a longer sequence (in terms of number of events  matched)
517                     is more specific than a shorter sequence;
518
519              (c)    if the modifiers specified in one pattern are a subset of
520                     the modifiers in another pattern, then the  pattern  with
521                     more modifiers is more specific.
522
523              (d)    a  virtual  event  whose  physical  pattern  matches  the
524                     sequence is less specific than the same physical  pattern
525                     that is not associated with a virtual event.
526
527              (e)    given a sequence that matches two or more virtual events,
528                     one of the virtual events will be chosen, but  the  order
529                     is undefined.
530
531       If  the  matching  sequences  contain  more  than one event, then tests
532       (c)-(e) are applied in order from the most recent event  to  the  least
533       recent event in the sequences.  If these tests fail to determine a win‐
534       ner, then the most recently registered sequence is the winner.
535
536       If there are two (or more) virtual events that are  both  triggered  by
537       the  same  sequence,  and both of those virtual events are bound to the
538       same window tag, then only one of the virtual events will be triggered,
539       and it will be picked at random:
540              event add <<Paste>> <Control-y>
541              event add <<Paste>> <Button-2>
542              event add <<Scroll>> <Button-2>
543              bind Entry <<Paste>> {puts Paste}
544              bind Entry <<Scroll>> {puts Scroll}
545       If the user types Control-y, the <<Paste>> binding will be invoked, but
546       if the user presses button 2 then one of either the  <<Paste>>  or  the
547       <<Scroll>> bindings will be invoked, but exactly which one gets invoked
548       is undefined.
549
550       If an X event does not match any of the  existing  bindings,  then  the
551       event is ignored.  An unbound event is not considered to be an error.
552

MULTI-EVENT SEQUENCES AND IGNORED EVENTS

554       When  a  sequence  specified  in  a bind command contains more than one
555       event pattern, then its script is executed whenever the  recent  events
556       (leading  up  to  and  including  the  current  event)  match the given
557       sequence.  This means, for example, that if button 1 is clicked repeat‐
558       edly  the  sequence <Double-ButtonPress-1> will match each button press
559       but the first.  If extraneous events that would prevent a  match  occur
560       in  the  middle  of  an  event  sequence then the extraneous events are
561       ignored unless they are KeyPress or ButtonPress events.   For  example,
562       <Double-ButtonPress-1>  will  match  a sequence of presses of button 1,
563       even though there will be ButtonRelease  events  (and  possibly  Motion
564       events)  between the ButtonPress events.  Furthermore, a KeyPress event
565       may be preceded by any number of other  KeyPress  events  for  modifier
566       keys  without  the  modifier keys preventing a match.  For example, the
567       event sequence aB will match a press of the a key, a release of  the  a
568       key,  a press of the Shift key, and a press of the b key:  the press of
569       Shift is ignored because it is a modifier  key.   Finally,  if  several
570       Motion events occur in a row, only the last one is used for purposes of
571       matching binding sequences.
572

ERRORS

574       If an error occurs in executing the script for a binding then the bger‐
575       ror mechanism is used to report the error.  The bgerror command will be
576       executed at global level (outside the context of any Tcl procedure).
577

EXAMPLES

579       Arrange for a string describing the motion of the mouse to  be  printed
580       out when the mouse is double-clicked:
581              bind . <Double-1> {
582                  puts "hi from (%x,%y)"
583              }
584
585       A little GUI that displays what the keysym name of the last key pressed
586       is:
587              set keysym "Press any key"
588              pack [label .l -textvariable keysym -padx 2m -pady 1m]
589              bind . <Key> {
590                  set keysym "You pressed %K"
591              }
592

SEE ALSO

594       bgerror(n), bindtags(n), event(n), focus(n), grab(n), keysyms(n)
595

KEYWORDS

597       binding, event
598
599
600
601Tk                                    8.0                              bind(n)
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