MENU(9) MENU(9)
NAME
menu - Create and manipulate menu widgets
SYNOPSIS
menu pathName ?options?
STANDARD OPTIONS
-activebackground -borderwidth -foreground
-activeforeground -disabledcolor -relief
-background -font
WIDGET-SPECIFIC OPTIONS
-postcommand command
If this option is specified then it provides a Tk com-
mand to execute each time the menu is posted. The com-
mand is invoked by the post widget command before post-
ing the menu.
-selectcolor colour
For menu entries that are check buttons or radio but-
tons, this option specifies the colour to display in
the indicator when the check button or radio button is
selected.
INTRODUCTION
The menu command creates a new top-level window (given by
the pathName argument) and makes it into a menu widget.
Additional options, described above, may be specified on the
command line to configure aspects of the menu such as its
colours and font. The menu command returns its pathName
argument. At the time this command is invoked, there must
not exist a window named pathName.
A menu is a widget that displays a collection of one-line
entries arranged in a column. There exist several different
types of entries, each with different properties. Entries
of different types may be combined in a single menu. Menu
entries are not the same as entry widgets. In fact, menu
entries are not even distinct widgets; the entire menu is
one widget.
Menu entries are displayed with up to three separate fields.
The main field is a label in the form of a text string, a
bitmap, or an image, controlled by the -label, -bitmap, and
-image options for the entry. The second field is a marker
for cascade entries, showing that the entry will post a cas-
cade menu. It is displayed at the right-hand edge of the
entry. The third field is an indicator. The indicator is
present only for checkbutton or radiobutton entries. It
indicates whether the entry is selected or not, and is
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displayed to the left of the entry's string.
In normal use, an entry becomes active (displays itself dif-
ferently) whenever the mouse pointer is over the entry. If
a mouse button is released over the entry then the entry is
invoked. The effect of invocation is different for each
type of entry; these effects are described below in the sec-
tions on individual entries.
Entries may be disabled, which causes their labels and
accelerators to be displayed with dimmer colours. The
default menu bindings will not allow a disabled entry to be
activated or invoked. Disabled entries may be re-enabled,
at which point it becomes possible to activate and invoke
them again.
COMMAND ENTRIES
The most common kind of menu entry is a command entry, which
behaves much like a button widget. When a command entry is
invoked, a Tk command is executed. The Tk command is speci-
fied with the -command option.
SEPARATOR ENTRIES
A separator is an entry that is displayed as a horizontal
dividing line. A separator may not be activated or invoked,
and it has no behaviour other than its display appearance.
CHECKBUTTON ENTRIES
A checkbutton menu entry behaves much like a checkbutton
widget. When it is invoked it toggles back and forth
between the selected and deselected states. When the entry
is selected, the value ``1'' is stored in a particular glo-
bal variable (as determined by -variable option for the
entry); when the entry is deselected the value ``0'' is
stored in the global variable. An indicator box is dis-
played to the left of the label in a checkbutton entry. If
the entry is selected then the indicator's center is dis-
played in the colour given by the -selectcolor option for
the entry; otherwise the indicator's center is displayed in
the background colour for the menu. If a -command option is
specified for a checkbutton entry, then its value is evalu-
ated as a Tk command each time the entry is invoked; this
happens after toggling the entry's selected state.
RADIOBUTTON ENTRIES
A radiobutton menu entry behaves much like a radiobutton
widget. Radiobutton entries are organized in groups of
which only one entry may be selected at a time. Whenever a
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particular entry becomes selected it stores a particular
value into a particular global variable (as determined by
the -value and -variable options for the entry). This
action causes any previously-selected entry in the same
group to deselect itself. Once an entry has become
selected, any change to the entry's associated variable will
cause the entry to deselect itself. Grouping of radiobutton
entries is determined by their associated variables: if two
entries have the same associated variable then they are in
the same group. An indicator diamond is displayed to the
left of the label in each radiobutton entry. If the entry
is selected then the indicator's center is displayed in the
colour given by the -selectcolor option for the entry; oth-
erwise the indicator's center is displayed in the background
colour for the menu. If a -command option is specified for
a radiobutton entry, then its value is evaluated as a Tk
command each time the entry is invoked; this happens after
selecting the entry.
CASCADE ENTRIES
A cascade entry is one with an associated menu (determined
by the -menu option). Cascade entries allow the construc-
tion of cascading menus. The postcascade widget command can
be used to post and unpost the associated menu just to the
right of the cascade entry. The associated menu must be a
child of the menu containing the cascade entry (this is
needed in order for menu traversal to work correctly).
A cascade entry posts its associated menu by invoking a Tk
command of the form
menu post x y
where menu is the path name of the associated menu, and x
and y are the screen coordinates of the upper-right corner
of the cascade entry. The lower-level menu is unposted by
executing a Tk command with the form
menu unpost
where menu is the name of the associated menu.
If a -command option is specified for a cascade entry then
it is evaluated as a Tk command whenever the entry is
invoked.
WIDGET COMMAND
The menu command creates a new Tk command whose name is
pathName. This command may be used to invoke various opera-
tions on the widget. It has the following general form:
pathName option ?arg arg ...?
Option and the args determine the exact behaviour of the
command.
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Many of the widget commands for a menu take as one argument
an indicator of which entry of the menu to operate on.
These indicators are called indexes and may be specified in
any of the following forms:
number Specifies the entry numerically, where 0 corre-
sponds to the top-most entry of the menu, 1 to
the entry below it, and so on.
active Indicates the entry that is currently active.
If no entry is active then this form is equiva-
lent to none. This form may not be abbreviated.
end Indicates the bottommost entry in the menu. If
there are no entries in the menu then this form
is equivalent to none. This form may not be
abbreviated.
none Indicates ``no entry at all''; this is used
most commonly with the activate option to deac-
tivate all the entries in the menu. In most
cases the specification of none causes nothing
to happen in the widget command. This form may
not be abbreviated.
@number In this form, number is treated as a y-
coordinate in the menu's window; the entry
closest to that y-coordinate is used. For exam-
ple, ``@0'' indicates the top-most entry in the
window.
The following widget commands are possible for menu widgets:
pathName activate index
Change the state of the entry indicated by index to
active and redisplay it using its active colours. Any
previously-active entry is deactivated. If index is
specified as none, or if the specified entry is dis-
abled, then the menu ends up with no active entry.
Returns an empty string.
pathName add type ?option value option value ...?
Add a new entry to the bottom of the menu. The new
entry's type is given by type and must be one of cas-
cade, checkbutton, command, radiobutton, or separator.
If additional arguments are present, they specify any
of the following options:
-activebackground value
Specifies a background colour to use for display-
ing this entry when it is active. If this option
is not specified then the activebackground option
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for the overall menu is used. This option is not
available for separator entries.
-activeforeground value
Specifies a foreground colour to use for display-
ing this entry when it is active. If this option
is not specified then the activeforeground option
for the overall menu is used. This option is not
available for separator entries.
-background value
Specifies a background colour to use for display-
ing this entry when it is in the normal state
(neither active nor disabled). If this option is
not specified then the background option for the
overall menu is used. This option is not avail-
able for separator entries.
-bitmap bitmap
Specifies a bitmap to display in the menu instead
of a textual label. This option overrides the
-label option but may be reset to an empty string
to enable a textual label to be displayed. If a
-image option has been specified, it overrides
-bitmap. This option is not available for separa-
tor entries.
-command value
Specifies a Tk command to execute when the menu
entry is invoked. Not available for separator
entries.
-font value
Specifies the font to use when drawing the label
or accelerator string in this entry. If this
option is not specified then the font option for
the overall menu is used. This option is not
available for separator entries.
-foreground value
Specifies a foreground colour to use for display-
ing this entry when it is in the normal state
(neither active nor disabled). If this option is
not specified then the foreground option for the
overall menu is used. This option is not avail-
able for separator entries.
-image value
Specifies an image to display in the menu instead
of a text string or bitmap The image must have
been created by some previous invocation of image
create. This option overrides the -label and
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-bitmap options but may be reset to an empty
string to enable a textual or bitmap label to be
displayed. This option is not available for sepa-
rator entries.
-label value
Specifies a string to display as an identifying
label in the menu entry. Not available for sepa-
rator entries.
-menu value
Available only for cascade entries. Specifies the
path name of the submenu associated with this
entry. The submenu must be a child of the menu.
-selectcolor value
Available only for checkbutton and radiobutton
entries. Specifies the colour to display in the
indicator when the entry is selected. If this
option is not specified then the selectcolor
option for the menu determines the indicator
colour.
-selectimage value
Available only for checkbutton and radiobutton
entries. Specifies an image to display in the
entry (in place of the -image option) when it is
selected. Value is the name of an image, which
must have been created by some previous invocation
of image create. This option is ignored unless
the -image option has been specified.
-state value
Specifies one of three states for the entry: nor-
mal, active, or disabled. In normal state the
entry is displayed using the foreground and back-
ground colours. The active state is typically
used when the pointer is over the entry. In
active state the entry is displayed using the
activeforeground and activebackground colours.
Disabled state means that the entry should be
insensitive: the default bindings will refuse to
activate or invoke the entry. In this state the
entry is displayed according to the disabledcolor
and background colours. This option is not avail-
able for separator entries.
-underline value
Specifies the integer index of a character to
underline in the entry. This option is also
queried by the default bindings and used to imple-
ment keyboard traversal. 0 corresponds to the
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first character of the text displayed in the
entry, 1 to the next character, and so on. If a
bitmap or image is displayed in the entry then
this option is ignored. This option is not avail-
able for separator entries.
-value value
Available only for radiobutton entries. Specifies
the value to store in the entry's associated vari-
able when the entry is selected. If an empty
string is specified, then the -label option for
the entry as the value to store in the variable.
-variable value
Available only for checkbutton and radiobutton
entries. Specifies the name of a global value to
set when the entry is selected. For checkbutton
entries the variable is also set when the entry is
deselected. For radiobutton entries, changing the
variable causes the currently-selected entry to
deselect itself.
The add widget command returns an empty string.
pathName cget option
Returns the current value of the configuration option
given by option. Option may have any of the values
accepted by the menu command.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the wid-
get. If no option is specified, returns a list of all
of the available options for pathName. If one or more
option-value pairs are specified, then the command mod-
ifies the given widget option(s) to have the given
value(s); in this case the command returns an empty
string. Option may have any of the values accepted by
the menu command.
pathName delete index1 ?index2?
Delete all of the menu entries between index1 and
index2 inclusive. If index2 is omitted then it
defaults to index1.
pathName entrycget index option
Returns the current value of a configuration option for
the entry given by index. Option may have any of the
values accepted by the add widget command.
pathName entryconfigure index ?options?
This command is similar to the configure command,
except that it applies to the options for an individual
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entry, whereas configure applies to the options for the
menu as a whole. Options may have any of the values
accepted by the add widget command. If options are
specified, options are modified as indicated in the
command and the command returns an empty string.
pathName index index
Returns the numerical index corresponding to index, or
none if index was specified as none.
pathName insert index type ?option value option value ...?
Same as the add widget command except that it inserts
the new entry just before the entry given by index,
instead of appending to the end of the menu. The type,
option, and value arguments have the same interpreta-
tion as for the add widget command.
pathName invoke index
Invoke the action of the menu entry. See the sections
on the individual entries above for details on what
happens. If the menu entry is disabled then nothing
happens. If the entry has a command associated with it
then the result of that command is returned as the
result of the invoke widget command. Otherwise the
result is an empty string. Note: invoking a menu
entry does not automatically unpost the menu; the
default bindings normally take care of this before
invoking the invoke widget command.
pathName post x y
Arrange for the menu to be displayed on the screen at
the screen coordinates given by x and y. These coordi-
nates are adjusted if necessary to guarantee that the
entire menu is visible on the screen. This command
normally returns an empty string. If the postcommand
option has been specified, then its value is executed
as a Tk script before posting the menu and the result
of that script is returned as the result of the post
widget command. If an error returns while executing
the command, then the error is returned without posting
the menu.
pathName postcascade index
Posts the submenu associated with the cascade entry
given by index, and unposts any previously posted sub-
menu. If index doesn't correspond to a cascade entry,
or if pathName isn't posted, the command has no effect
except to unpost any currently posted submenu.
pathName type index
Returns the type of the menu entry given by index.
This is the type argument passed to the add widget
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command when the entry was created, such as command or
separator.
pathName unpost
Unmap the window so that it is no longer displayed. If
a lower-level cascaded menu is posted, unpost that
menu. Returns an empty string.
pathName yposition index
Returns a decimal string giving the y-coordinate within
the menu window of the topmost pixel in the entry spec-
ified by index.
DEFAULT BINDINGS
Tk automatically creates bindings for menus that give them
the following default behaviour:
[1] When the mouse enters a menu, the entry underneath the
mouse cursor activates; as the mouse moves around the
menu, the active entry changes to track the mouse.
[2] When the mouse leaves a menu all of the entries in the
menu deactivate, except in the special case where the
mouse moves from a menu to a cascaded submenu.
[3] When a button is released over a menu, the active entry
(if any) is invoked. The menu also unposts unless it
is a torn-off menu.
[4] If any of the entries in a menu have letters underlined
with with -underline option, then pressing one of the
underlined letters (or its upper-case or lower-case
equivalent) invokes that entry and unposts the menu.
Disabled menu entries are non-responsive: they don't acti-
vate and they ignore mouse button presses and releases.
The behaviour of menus can be changed by defining new bind-
ings for individual widgets.
BUGS
The first time any colour option of an entry is configured,
all of the menu colour option values are captured and set in
the entry. Any subsequent changes to the menu's colour
options will not be reflected in the entry.
SEE ALSO
options(9), types(9)
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