tk4.2 User Commands - menu
NAME
menu - Create and manipulate menu widgets
SYNOPSIS
menu pathName ?options?
STANDARD OPTIONS
-activebackground -background -disabledforeground-relief
-activeborderwidth -borderwidth -font-takefocus
-activeforeground -cursor -foreground
See the options manual entry for details on the standard
options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-postcommand
Database Name: postCommand
Database Class: Command
If this option is specified then it provides a Tcl 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.
Command-Line Name:-selectcolor
Database Name: selectColor
Database Class: Background
For menu entries that are check buttons or radio but-
tons, this option specifies the color to display in the
indicator when the check button or radio button is
selected.
Command-Line Name:-tearoff
Database Name: tearOff
Database Class: TearOff
This option must have a proper boolean value, which
specifies whether or not the menu should include a
tear-off entry at the top. If so, it will exist as
entry 0 of the menu and the other entries will number
starting at 1. The default menu bindings arrange for
the menu to be torn off when the tear-off entry is
invoked.
Command-Line Name:-tearoffcommand
Database Name: tearOffCommand
Database Class: TearOffCommand
If this option has a non-empty value, then it specifies
a Tcl command to invoke whenever the menu is torn off.
The actual command will consist of the value of this
option, followed by a space, followed by the name of
the menu window, followed by a space, followed by the
name of the name of the torn off menu window. For
example, if the option's is ``a b'' and menu .x.y is
torn off to create a new menu .x.tearoff1, then the
command ``a b .x.y .x.tearoff1'' will be invoked.
Command-Line Name:-transient
Database Name: transient
Database Class: Transient
This option must have a boolean value. True means that
the menu is used on a transient basis, e.g. as a pop-
up, pull-down, or cascaded menu. False means that the
menu will be displayed on the screen continuously, for
example as a torn-off menu. If the option is true, no
window manager border will be displayed around the menu
and redisplay will be optimized using X's ``save
under'' facility.
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 or in the option database to configure aspects
of the menu such as its colors and font. The menu command
returns its pathName argument. At the time this command is
invoked, there must not exist a window named pathName, but
pathName's parent must exist.
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. If the -accelerator option
is specified for an entry then a second textual field is
displayed to the right of the label. The accelerator typi-
cally describes a keystroke sequence that may be typed in
the application to cause the same result as invoking the
menu 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
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 colors. 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 Tcl command is executed. The Tcl command is
specified 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 behavior 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, a particular value is stored in a particular
global variable (as determined by the -onvalue and -variable
options for the entry); when the entry is deselected
another value (determined by the -offvalue option) is stored
in the global variable. An indicator box is displayed to
the left of the label in a checkbutton entry. If the entry
is selected then the indicator's center is displayed in the
color given by the -selectcolor option for the entry; other-
wise the indicator's center is displayed in the background
color for the menu. If a -command option is specified for a
checkbutton entry, then its value is evaluated as a Tcl com-
mand 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
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
color given by the -selectcolor option for the entry; other-
wise the indicator's center is displayed in the background
color for the menu. If a -command option is specified for a
radiobutton entry, then its value is evaluated as a Tcl com-
mand 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 Tcl
command of the form
menu post x y
where menu is the path name of the associated menu, and x
and y are the root-window coordinates of the upper-right
corner of the cascade entry. The lower-level menu is
unposted by executing a Tcl 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 Tcl command whenever the entry is
invoked.
TEAR-OFF ENTRIES
A tear-off entry appears at the top of the menu if enabled
with the tearOff option. It is not like other menu entries
in that it cannot be created with the add widget command and
cannot be deleted with the delete widget command. When a
tear-off entry is created it appears as a dashed line at the
top of the menu. Under the default bindings, invoking the
tear-off entry causes a torn-off copy to be made of the menu
and all of its submenus.
WIDGET COMMAND
The menu command creates a new Tcl 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 behavior of the com-
mand.
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
corresponds 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
equivalent to none. This form may not be abbre-
viated.
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.
last Same as end.
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.
pattern If the index doesn't satisfy one of the above
forms then this form is used. Pattern is
pattern-matched against the label of each entry
in the menu, in order from the top down, until a
matching entry is found. The rules of
Tcl_StringMatch are used.
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 colors. 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,
or a unique abbreviation of one of the above. If addi-
tional arguments are present, they specify any of the
following options:
-activebackground value
Specifies a background color to use for displaying
this entry when it is active. If this option is
specified as an empty string (the default), then
the activeBackground option for the overall menu
is used. If the tk_strictMotif variable has been
set to request strict Motif compliance, then this
option is ignored and the - background option is
used in its place. This option is not available
for separator or tear-off entries.
-activeforeground value
Specifies a foreground color to use for displaying
this entry when it is active. If this option is
specified as an empty string (the default), then
the activeForeground option for the overall menu
is used. This option is not available for separa-
tor or tear-off entries.
-accelerator value
Specifies a string to display at the right side of
the menu entry. Normally describes an accelerator
keystroke sequence that may be typed to invoke the
same function as the menu entry. This option is
not available for separator or tear-off entries.
-background value
Specifies a background color to use for displaying
this entry when it is in the normal state (neither
active nor disabled). If this option is specified
as an empty string (the default), then the
background option for the overall menu is used.
This option is not available for separator or
tear-off entries.
-bitmap value
Specifies a bitmap to display in the menu instead
of a textual label, in any of the forms accepted
by Tk_GetBitmap. 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 or tear-off entries.
-command value
Specifies a Tcl command to execute when the menu
entry is invoked. Not available for separator or
tear-off entries.
-font value
Specifies the font to use when drawing the label
or accelerator string in this entry. If this
option is specified as an empty string (the
default) then the font option for the overall menu
is used. This option is not available for separa-
tor or tear-off entries.
-foreground value
Specifies a foreground color to use for displaying
this entry when it is in the normal state (neither
active nor disabled). If this option is specified
as an empty string (the default), then the fore-
ground option for the overall menu is used. This
option is not available for separator or tear-off
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 -
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
separator or tear-off entries.
-indicatoron value
Available only for checkbutton and radiobutton
entries. Value is a boolean that determines
whether or not the indicator should be displayed.
-label value
Specifies a string to display as an identifying
label in the menu entry. Not available for
separator or tear-off 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.
-offvalue value
Available only for checkbutton entries. Specifies
the value to store in the entry's associated vari-
able when the entry is deselected.
-onvalue value
Available only for checkbutton entries. Specifies
the value to store in the entry's associated vari-
able when the entry is selected.
-selectcolor value
Available only for checkbutton and radiobutton
entries. Specifies the color to display in the
indicator when the entry is selected. If the
value is an empty string (the default) then the
selectColor option for the menu determines the
indicator color.
-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 option for
the menu and the background option from the entry
or the menu. The active state is typically used
when the pointer is over the entry. In active
state the entry is displayed using the activeFore-
ground option for the menu along with the
activebackground option from the entry. 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 disabledForeground
option for the menu and the background option from
the entry. This option is not available 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
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 or tear-off 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
widget. If no option is specified, returns a list
describing all of the available options for pathName
(see Tk_ConfigureInfo for information on the format of
this list). If option is specified with no value, then
the command returns a list describing the one named
option (this list will be identical to the correspond-
ing sublist of the value returned if no option is
specified). If one or more option - value pairs are
specified, then the command modifies 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. Attempts to delete a tear-off menu
entry are ignored (instead, you should change the tear-
Off option to remove the tear-off entry).
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
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. If no
options are specified, returns a list describing the
current options for entry index (see Tk_ConfigureInfo
for information on the format of this list).
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. It is not possible
to insert new menu entries before the tear-off entry,
if the menu has one.
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 root-window coordinates given by x and y. These
coordinates 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 Tcl 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 com-
mand when the entry was created, such as command or
separator, or tearoff for a tear-off entry.
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
specified by index.
MENU CONFIGURATIONS
The default bindings support four different ways of using
menus:
Pulldown Menus
This is the most common case. You create one menubut-
ton widget for each top-level menu, and typically you
arrange a series of menubuttons in a row in a menubar
window. You also create the top-level menus and any
cascaded submenus, and tie them together with - menu
options in menubuttons and cascade menu entries. The
top-level menu must be a child of the menubutton, and
each submenu must be a child of the menu that refers to
it. Once you have done this, the default bindings will
allow users to traverse and invoke the tree of menus
via its menubutton; see the menubutton manual entry
for details.
Popup Menus
Popup menus typically post in response to a mouse but-
ton press or keystroke. You create the popup menus and
any cascaded submenus, then you call the tk_popup pro-
cedure at the appropriate time to post the top-level
menu.
Option Menus
An option menu consists of a menubutton with an associ-
ated menu that allows you to select one of several
values. The current value is displayed in the menubut-
ton and is also stored in a global variable. Use the
tk_optionMenu procedure to create option menubuttons
and their menus.
Torn-off Menus
You create a torn-off menu by invoking the tear-off
entry at the top of an existing menu. The default
bindings will create a new menu that is a copy of the
original menu and leave it permanently posted as a
top-level window. The torn-off menu behaves just the
same as the original menu.
DEFAULT BINDINGS
Tk automatically creates class bindings for menus that give
them the following default behavior:
[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] The Space and Return keys invoke the active entry and
unpost the menu.
[5] 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.
[6] The Escape key aborts a menu selection in progress
without invoking any entry. It also unposts the menu
unless it is a torn-off menu.
[7] The Up and Down keys activate the next higher or lower
entry in the menu. When one end of the menu is
reached, the active entry wraps around to the other
end.
[8] The Left key moves to the next menu to the left. If
the current menu is a cascaded submenu, then the sub-
menu is unposted and the current menu entry becomes the
cascade entry in the parent. If the current menu is a
top-level menu posted from a menubutton, then the
current menubutton is unposted and the next menubutton
to the left is posted. Otherwise the key has no
effect. The left-right order of menubuttons is deter-
mined by their stacking order: Tk assumes that the
lowest menubutton (which by default is the first one
created) is on the left.
[9] The Right key moves to the next menu to the right. If
the current entry is a cascade entry, then the submenu
is posted and the current menu entry becomes the first
entry in the submenu. Otherwise, if the current menu
was posted from a menubutton, then the current menubut-
ton is unposted and the next menubutton to the right is
posted.
Disabled menu entries are non-responsive: they don't
activate and they ignore mouse button presses and releases.
The behavior of menus can be changed by defining new bind-
ings for individual widgets or by redefining the class bind-
ings.
BUGS
At present it isn't possible to use the option database to
specify values for the options to individual entries.
KEYWORDS
menu, widget