Binding User Interface
by Brent Welch
A number of keystroke bindings, already defined by
exmh, invoke different Tcl commands. You can change the
bindings and add bindings for new commands via the Bind dialog.
Open the dialog from the Commands menu entry under the
Bindings menu. The dialog presents two columns of commands and
their bindings, plus an area at the top to define a new binding.
Binding Syntax. Here is a brief summary of the Tk bind
syntax. To get the complete story, consult the Tk manual page for
the bind command. The Tk syntax for the bindings events is:
<modifier-type-detail>
In that syntax,
-
A modifier is a key that you hold down while pressing
another key. The modifiers you are likely to use are
Control,
Shift, and
Meta. Capitalization of these keywords is significant
-- that is, uppercase and lowercase letters are not equivalent.
-
The type is the event type; it can be left out if the
detail part implies it. The types you'll usually use are
Key and
Button.
-
The detail specifies the key or button number for the
event. Keys are named by their X keysym. For the letters and
digits, the keysym is just the letter or digit, e.g.,
<Key-a>, which can be shortened
to <a>. For punctuation, however, the keysyms are
words. Some examples are
<comma>,
<period>,
<asciicircum>,
<question>, and
<exclam>. Again, the Key type is omitted.
-
The capitalization used with the modifiers, types, and keysyms
is significant. Watch out for keysyms like BackSpace!
Perhaps the easiest way to figure out the keysym is to use the
following Tcl/Tk command. Run the Tcl/Tk shell, wish, and
enter the command shown in
the next Example. A little window will open.
Type characters into that window, and you'll see keysym
information underneath the wish command line.
In the example below, after starting wish and typing
the bind command, I moved the mouse to the little window.
I pressed and held down the left <Shift> key, pressed the
<g> key and the <dollar> key, released the
<Shift> key, and pressed the <q> key. I moved the
mouse back to the shell window and typed <Control-d> to
quit wish.
Example: Finding an X keysym
unix$ wish
% bind . <Any-Key> {puts stdout "keysym = %K letter = %A"}
% keysym = Shift_L letter =
keysym = G letter = G
keysym = dollar letter = $
keysym = q letter = q
CTRL-D
unix$