NAME
       event  - Miscellaneous event facilities: define virtual events and gen-
       erate events

SYNOPSIS
       event option ?arg arg ...?


DESCRIPTION
       The event command provides several facilities for dealing  with  window
       system events, such as defining virtual events and synthesizing events.
       The command has several different forms, determined by the first  argu-
       ment.  The following forms are currently supported:

       event add <<virtual>> sequence ?sequence ...?
              Associates  the  virtual  event  virtual with the physical event
              sequence(s) given by the sequence arguments, so that the virtual
              event  will  trigger  whenever  any one of the sequences occurs.
              Virtual may be any string value and sequence may have any of the
              values  allowed  for  the sequence argument to the bind command.
              If virtual is already defined, the new physical event  sequences
              add to the existing sequences for the event.

       event delete <<virtual>> ?sequence sequence ...?
              Deletes  each  of  the  sequences from those associated with the
              virtual event given by virtual.  Virtual may be any string value
              and sequence may have any of the values allowed for the sequence
              argument to the bind command.  Any sequences not currently asso-
              ciated  with  virtual  are  ignored.  If no sequence argument is
              provided, all physical event sequences are removed for  virtual,
              so that the virtual event will not trigger anymore.

       event generate window event ?option value option value ...?
              Generates  a  window  event  and arranges for it to be processed
              just as if it had come from the window system.  Window gives the
              path  name  of the window for which the event will be generated;
              it may also be an identifier (such as returned by winfo  id)  as
              long  as  it  is for a window in the current application.  Event
              provides a basic description of the event, such  as  <Shift-But-
              ton-2>  or  <<Paste>>.   If  Window is empty the whole screen is
              meant, and coordinates are relative to the  screen.   Event  may
              have  any  of the forms allowed for the sequence argument of the
              bind command except that it must consist of a single event  pat-
              tern, not a sequence.  Option-value pairs may be used to specify
              additional attributes of the event, such as the x  and  y  mouse
              position;   see  EVENT FIELDS below.  If the -when option is not
              specified, the event is processed immediately:  all of the  han-
              dlers for the event will complete before the event generate com-
              mand returns.  If the -when option is specified then  it  deter-
              mines  when the event is processed.  Certain events, such as key
              events, require that the window has focus to receive  the  event
              properly.

       event info ?<<virtual>>?
              Returns  information  about  virtual events.  If the <<virtual>>
              argument is omitted, the return value is a list of all the  vir-
              tual events that are currently defined.  If <<virtual>> is spec-
              ified then the return value is a list  whose  elements  are  the
              physical event sequences currently defined for the given virtual
              event;  if the virtual event is not defined then an empty string
              is returned.

EVENT FIELDS
       The  following  options  are  supported for the event generate command.
       These correspond to the ``%'' expansions allowed in binding scripts for
       the bind command.

       -above window
              Window specifies the above field for the event, either as a win-
              dow path name or as an integer window id.  Valid  for  Configure
              events.  Corresponds to the %a substitution for binding scripts.

       -borderwidth size
              Size must be a screen distance;  it specifies  the  border_width
              field  for  the event.  Valid for Configure events.  Corresponds
              to the %B substitution for binding scripts.

       -button number
              Number must be an integer;  it specifies the detail field for  a
              ButtonPress  or ButtonRelease event, overriding any button  num-
              ber provided in the base event argument.  Corresponds to the  %b
              substitution for binding scripts.

       -count number
              Number must be an integer;  it specifies the count field for the
              event.  Valid for Expose events.  Corresponds to the %c  substi-
              tution for binding scripts.

       -delta number
              Number must be an integer;  it specifies the delta field for the
              MouseWheel event.  The delta refers to the direction and  magni-
              tude  the  mouse  wheel  was  rotated.   Note the value is not a
              screen distance but are units of  motion  in  the  mouse  wheel.
              Typically  these  values are multiples of 120.  For example, 120
              should scroll the text widget up 4 lines and -240  would  scroll
              the  text  widget  down  8  lines.  Of course, other widgets may
              define different behaviors for mouse wheel motion.   This  field
              corresponds to the %D substitution for binding scripts.

       -detail detail
              Detail  specifies the detail field for the event and must be one
              of the following:

                     NotifyAncestor          NotifyNonlinearVirtual
                     NotifyDetailNone        NotifyPointer
                     NotifyInferior          NotifyPointerRoot
                     NotifyNonlinear         NotifyVirtual

              Valid for Enter, Leave, FocusIn  and  FocusOut  events.   Corre-
              sponds to the %d substitution for binding scripts.

       -focus boolean
              Boolean  must  be a boolean value;  it specifies the focus field
              for the event.  Valid for Enter and Leave  events.   Corresponds
              to the %f substitution for binding scripts.

       -height size
              Size  must  be a screen distance;  it specifies the height field
              for the event.  Valid for Configure events.  Corresponds to  the
              %h substitution for binding scripts.

       -keycode number
              Number   must be an integer;  it specifies the keycode field for
              the event.  Valid for KeyPress and  KeyRelease  events.   Corre-
              sponds to the %k substitution for binding scripts.

       -keysym name
              Name  must  be  the name of a valid keysym, such as g, space, or
              Return;  its corresponding keycode value is used as the  keycode
              field  for  event,  overriding  any detail specified in the base
              event argument.  Valid for KeyPress and KeyRelease events.  Cor-
              responds to the %K substitution for binding scripts.

       -mode notify
              Notify specifies the mode field for the event and must be one of
              NotifyNormal, NotifyGrab, NotifyUngrab,  or  NotifyWhileGrabbed.
              Valid  for  Enter,  Leave, FocusIn, and FocusOut events.  Corre-
              sponds to the %m substitution for binding scripts.

       -override boolean
              Boolean must be a boolean value;  it specifies the  override_re-
              direct  field  for the event.  Valid for Map, Reparent, and Con-
              figure events.  Corresponds to the %o substitution  for  binding
              scripts.

       -place where
              Where  specifies  the  place  field  for  the event;  it must be
              either PlaceOnTop or PlaceOnBottom.  Valid for Circulate events.
              Corresponds to the %p substitution for binding scripts.

       -root window
              Window  must  be  either a window path name or an integer window
              identifier;  it specifies the root field for the  event.   Valid
              for  KeyPress,  KeyRelease,  ButtonPress,  ButtonRelease, Enter,
              Leave, and Motion events.  Corresponds to  the  %R  substitution
              for binding scripts.

       -rootx coord
              Coord  must be a screen distance;  it specifies the x_root field
              for the event.  Valid  for  KeyPress,  KeyRelease,  ButtonPress,
              ButtonRelease,  Enter, Leave, and Motion events.  Corresponds to
              the %X substitution for binding scripts.

       -rooty coord
              Coord must be a screen distance;  it specifies the y_root  field
              for  the  event.   Valid  for KeyPress, KeyRelease, ButtonPress,
              ButtonRelease, Enter, Leave, and Motion events.  Corresponds  to
              the %Y substitution for binding scripts.

       -sendevent boolean
              Boolean  must  be  a boolean value;  it specifies the send_event
              field for the event.  Valid for all events.  Corresponds to  the
              %E substitution for binding scripts.

       -serial number
              Number  must  be  an integer;  it specifies the serial field for
              the event.  Valid for all events.  Corresponds to the %# substi-
              tution for binding scripts.

       -state state
              State  specifies  the  state field for the event.  For KeyPress,
              KeyRelease, ButtonPress, ButtonRelease, Enter, Leave, and Motion
              events  it  must  be an integer value.  For Visibility events it
              must  be  one  of  VisibilityUnobscured,  VisibilityPartiallyOb-
              scured,  or  VisibilityFullyObscured.  This option overrides any
              modifiers such as Meta or Control specified in the  base  event.
              Corresponds to the %s substitution for binding scripts.

       -subwindow window
              Window  specifies the subwindow field for the event, either as a
              path name for a Tk widget or as an  integer  window  identifier.
              Valid  for  KeyPress,  KeyRelease,  ButtonPress,  ButtonRelease,
              Enter, Leave, and Motion events.  Similar to %S substitution for
              binding scripts.

       -time integer
              Integer  must  be an integer value;  it specifies the time field
              for the event.  Valid  for  KeyPress,  KeyRelease,  ButtonPress,
              ButtonRelease,  Enter, Leave, Motion, and Property events.  Cor-
              responds to the %t substitution for binding scripts.

       -warp boolean
              boolean must be a  boolean  value;   it  specifies  whether  the
              screen  pointer  should  be warped as well.  Valid for KeyPress,
              KeyRelease, ButtonPress, ButtonRelease, and Motion events.   The
              pointer will only warp to a window if it is mapped.

       -width size
              Size  must  be  a screen distance;  it specifies the width field
              for the event.  Valid for Configure events.  Corresponds to  the
              %w substitution for binding scripts.

       -when when
              When  determines when the event will be processed;  it must have
              one of the following values:

              now       Process the  event  immediately,  before  the  command
                        returns.   This  also  happens  if the -when option is
                        omitted.

              tail      Place the event on Tcl's event queue behind any events
                        already queued for this application.

              head      Place  the event at the front of Tcl's event queue, so
                        that it  will  be  handled  before  any  other  events
                        already queued.

              mark      Place  the event at the front of Tcl's event queue but
                        behind any other  events  already  queued  with  -when
                        mark.   This option is useful when generating a series
                        of events that should be processed in order but at the
                        front of the queue.

       -x coord
              Coord  must  be a screen distance;  it specifies the x field for
              the event.  Valid for KeyPress, KeyRelease, ButtonPress, Button-
              Release,  Motion,  Enter, Leave, Expose, Configure, Gravity, and
              Reparent events.  Corresponds to the %x substitution for binding
              scripts.   If  Window is empty the coordinate is relative to the
              screen, and this option corresponds to the %X  substitution  for
              binding scripts.

       -y coord
              Coord  must  be a screen distance;  it specifies the y field for
              the event.  Valid for KeyPress, KeyRelease, ButtonPress, Button-
              Release,  Motion,  Enter, Leave, Expose, Configure, Gravity, and
              Reparent events.  Corresponds to the %y substitution for binding
              scripts.   If  Window is empty the coordinate is relative to the
              screen, and this option corresponds to the %Y  substitution  for
              binding scripts.

       Any  options that are not specified when generating an event are filled
       with the value 0, except for serial, which is filled with  the  next  X
       event serial number.

VIRTUAL EVENT EXAMPLES
       In  order  for a virtual event binding to trigger, two things must hap-
       pen.  First, the virtual event must be defined with the event add  com-
       mand.  Second, a binding must be created for the virtual event with the
       bind command.  Consider the following virtual event definitions:
              event add <<Paste>> <Control-y>
              event add <<Paste>> <Button-2>
              event add <<Save>> <Control-X><Control-S>
              event add <<Save>> <Shift-F12>
       In the bind command, a virtual  event  can  be  bound  like  any  other
       builtin event type as follows:
              bind Entry <<Paste>> {%W insert [selection get]}
       The  double  angle brackets are used to specify that a virtual event is
       being bound.  If the user types Control-y or presses button 2, or if  a
       <<Paste>>  virtual  event  is synthesized with event generate, then the
       <<Paste>> binding will be invoked.

       If a virtual binding has the exact same sequence as a separate physical
       binding,  then the physical binding will take precedence.  Consider the
       following example:
              event add <<Paste>> <Control-y> <Meta-Control-y>
              bind Entry <Control-y> {puts Control-y}
              bind Entry <<Paste>> {puts Paste}
       When the user types Control-y the <Control-y> binding will be  invoked,
       because  a  physical  event  is considered more specific than a virtual
       event, all other things being equal.   However,  when  the  user  types
       Meta-Control-y  the <<Paste>> binding will be invoked, because the Meta
       modifier in the physical pattern associated with the virtual binding is
       more specific than the <Control-y> sequence for the physical event.

       Bindings  on  a  virtual  event may be created before the virtual event
       exists.  Indeed, the virtual event never actually needs to be  defined,
       for instance, on platforms where the specific virtual event would mean-
       ingless or ungeneratable.

       When a definition of a virtual event changes at run time,  all  windows
       will respond immediately to the new definition.  Starting from the pre-
       ceding example, if the following code is executed:
              bind <Entry> <Control-y> {}
              event add <<Paste>> <Key-F6>
       the behavior will  change  such  in  two  ways.   First,  the  shadowed
       <<Paste>>  binding will emerge.  Typing Control-y will no longer invoke
       the  <Control-y>  binding,  but  instead  invoke  the   virtual   event
       <<Paste>>.   Second,  pressing  the  F6  key  will  now also invoke the
       <<Paste>> binding.


SEE ALSO
       bind(n)


KEYWORDS
