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NAME
menu - Create and manipulate menu widgets
SYNOPSIS
menu pathName ?options?
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 text or a bitmap, which is determined by the -label or -bitmap option for the entry. The bitmap displayed by the -bitmap option can be manipulated by the -mask option. This option contains a bitmap that specifies which dots from the original bitmap should actually be displayed. If the -accelerator option is specified for an entry then a second textual field is displayed to the right of the label. The accelerator typically 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 a selector. The selector is present only for check-button or radio-button 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 colors. A disabled entry cannot 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.
CHECK-BUTTON ENTRIES
A check-button menu entry behaves much like a check-button 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. A selector box is displayed to the left of the label in a check-button entry. If the entry is selected then the box's center is displayed in the color given by the selector option for the menu; otherwise the box's center is displayed in the background color for the menu. If a -command option is specified for a check-button entry, then its value is evaluated as a Tcl command each time the entry is invoked; this happens after toggling the entry's selected state.
RADIO-BUTTON ENTRIES
A radio-button menu entry behaves much like a radio-button widget. Radio-button 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 radio-button entries is determined by their associated
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, x and y are the root-window coordinates of the upper-right corner of the cascade entry, and group is the name of the menu's group (as determined in its last post widget command). 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 each time the associated menu is posted (the evaluation occurs before the menu is posted).
WIDGET COMMAND
The menu command creates a new Tcl 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 behavior 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:
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 disabled, 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 cascade, checkbutton, command, radiobutton, or separator, or a unique abbreviation of one of the above. If additional arguments are present, they specify any of the following options:
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 corresponding 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. Returns an empty string.
pathName disable index
Change the state of the entry given by index to disabled and redisplay the entry using its disabled colors. Returns an empty string. This command is obsolete and will eventually be removed; use ``pathName entryconfigure index -state disabled'' instead.
pathName enable index
Change the state of the entry given by index to normal and redisplay the entry using its normal colors. Returns an empty string. This command is obsolete and will eventually be removed; use ``pathName entryconfigure index -state normal'' instead.
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 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. Normally the associated menubutton will take care of unposting the menu.
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 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.
DEFAULT BINDINGS
Tk automatically creates class bindings for menus that give them the following default behavior:
[1]
When the mouse cursor enters a menu, the entry underneath the mouse cursor is activated; as the mouse moves around the menu, the active entry changes to track the mouse.
[2]
When button 1 is released over a menu, the active entry (if any) is invoked.
[3]
A menu can be repositioned on the screen by dragging it with mouse button 2.
[4]
A number of other bindings are created to support keyboard menu traversal. See the manual entry for tk_bindForTraversal for details on these bindings.
Disabled menu entries are non-responsive: they don't activate and ignore mouse button presses and releases.
The behavior of menus can be changed by defining new bindings for individual widgets or by redefining the class bindings.
BUGS
At present it isn't possible to use the option database to specify values for the options to individual entries.
KEYWORDS
menu, widget