From: Hidetoshi NAGAI <nagai@...>
Date: 2005-10-11T23:02:28+09:00
Subject: Re: Tk, default event bindings

From: "Alexander Fleck" <Fleck@schleissheimer.de>
Subject: Tk, default event bindings
Date: Tue, 11 Oct 2005 18:56:54 +0900
Message-ID: <dig1vg$it9$02$1@news.t-online.com>
> do the Tk widgets own default event bindings? 

You can learn the default bindings of each widget with 
Tcl/Tk's manual pages. 
For example, on Tcl/Tk's man pages, description about default 
bindings of button widget is 
----------------------------------------------------------------------
DEFAULT BINDINGS
       Tk  automatically  creates class bindings for buttons that
       give them default behavior:

       [1]    A button activates whenever the mouse  passes  over
              it  and  deactivates  whenever the mouse leaves the
              button.  Under Windows, this binding is only active |
              when  mouse button 1 has been pressed over the but- |
              ton.

       [2]    A button's relief is  changed  to  sunken  whenever
              mouse  button 1 is pressed over the button, and the
              relief is restored to its original value when  but-
              ton 1 is later released.

       [3]    If  mouse  button  1  is  pressed over a button and
              later released  over  the  button,  the  button  is
              invoked.   However,  if  the  mouse is not over the
              button when button 1 is released, then  no  invoca-
              tion occurs.

       [4]    When  a  button  has the input focus, the space key
              causes the button to be invoked.

       If the button's state is disabled then none of  the  above
       actions occur:  the button is completely non-responsive.

       The  behavior  of  buttons  can be changed by defining new
       bindings for individual widgets or by redefining the class
       bindings.
----------------------------------------------------------------------

Therefore, 

> In tutorials I' ve seen, that the 'command proc' statement was used
> to add a procedure to a button event. But the procedure just gets
> started, when the button is clicked. 

you may be misunderstanding a bit.
'command proc' statement means to set 'command' option of the button 
widget to the procedure.
And the procedure assigned to 'command' option is called when the 
button in invoked.
That is, the 'command proc' statement doesn't change the bindings 
of the button.

> I thought I have to bind a
> procedure to a specific event. Does the procedure get bend to a
> default event when the "command proc" is used? 

If you want to know about bindings on Ruby/Tk, 
please read 'bind' and 'bindtags' manual pages of Tcl/Tk, 
and examples of binding control of Ruby/Tk (e.g. 
'ext/tk/sample/binding_sample.rb' and 'ext/tk/sample/bindtag_sample.rb'
on Ruby's source archive).

          Tcl/Tk                                 Ruby/Tk
-------------------------------------------------------------------------
bind target sequence script             target.bind(sequence, proc)
bind target sequence +script            target.bind_append(sequence, proc)

<modifier-modifier-type-detail>         'modifier-modifier-type-detail'
<<virual_event>>                        '<virtual_event>'

bindtags target                         target.bindtags
bindtags target taglist                 target.bindtags = taglist

-- 
Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)