MENU(9) Kernel Developer's Manual MENU(9)

menu - Create and manipulate menu widgets

menu pathName ?options?

-activebackground -borderwidth   -foreground
-activeforeground -disabledcolor -relief
-background       -font

If this option is specified then it provides a Tk command to execute each time the menu is posted. The command is invoked by the post widget command before posting the menu.
For menu entries that are check buttons or radio buttons, this option specifies the colour to display in the indicator when the check button or radio button is selected.

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 cascade 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 displayed to the left of the entry's string.

In normal use, an entry becomes active (displays itself differently) 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 sections 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.

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 specified with the -command option.

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.

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 global 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 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 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 evaluated as a Tk command each time the entry is invoked; this happens after toggling the entry's selected state.

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 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 radiobutton entry, then its value is evaluated as a Tk command each time the entry is invoked; this happens after selecting the entry.

A cascade entry is one with an associated menu (determined by the -menu option). Cascade entries allow the construction 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.

The menu command creates a new Tk command whose name is pathName. This command may be used to invoke various operations on the widget. It has the following general form:

pathName option ?arg arg ...?
Option and the args determine the exact behaviour of the command.

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:

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 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 deactivate 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 example, ``@0'' indicates the top-most entry in the window.

The following widget commands are possible for menu widgets:

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 disabled, then the menu ends up with no active entry. Returns an empty string.
Add a new entry to the bottom of the menu. The new entry's type is given by type and must be one of cascade, 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 displaying this entry when it is active. If this option is not specified then the activebackground option for the overall menu is used. This option is not available for separator entries.
-activeforeground value
Specifies a foreground colour to use for displaying 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 displaying 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 available 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 separator 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 displaying 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 available 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 -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 entries.
-label value
Specifies a string to display as an identifying label in the menu entry. Not available for separator 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: normal, active, or disabled. In normal state the entry is displayed using the foreground and background 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 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 implement 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 available for separator entries.
-value value
Available only for radiobutton entries. Specifies the value to store in the entry's associated variable 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.

Returns the current value of the configuration option given by option. Option may have any of the values accepted by the menu command.
Query or modify the configuration options of the widget. 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 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.
Delete all of the menu entries between index1 and index2 inclusive. If index2 is omitted then it defaults to index1.
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.
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.
Returns the numerical index corresponding to index, or none if index was specified as none.
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 interpretation as for the add widget command.
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.
Arrange for the menu to be displayed on the screen at the screen 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 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.
Posts the submenu associated with the cascade entry given by index, and unposts any previously posted submenu. 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.
Returns the type of the menu entry given by index. This is the type argument passed to the add widget command when the entry was created, such as command or separator.
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.
Returns a decimal string giving the y-coordinate within the menu window of the topmost pixel in the entry specified by index.

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 activate and they ignore mouse button presses and releases.

The behaviour of menus can be changed by defining new bindings for individual widgets.

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.

options (9), types (9)