---
name: "menu_driver"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/menu_driver"
---

# menu\_driver(3)

command-processing loop of the menu system

## NAME

**menu\_driver** - command-processing loop of the menu system

## SYNOPSIS

```
#include <menu.h>
```

**int menu\_driver(MENU \****menu***, int** *c***);**

## DESCRIPTION

**Once a menu has been posted (displayed), you should funnel input events to it** **through menu\_driver.  This routine has three major input cases:**

- •

  **The input is a menu navigation request.** **Navigation request codes are constants defined in** *menu.h*, **which are distinct from the key- and character codes** **returned by wgetch(3X).**

- •

  **The input is a printable character.** **Printable characters (which must be positive, less than 256) are** **checked according to the program's locale settings.**

- •

  **The input is the KEY\_MOUSE special key associated with an mouse event.**

**The menu driver requests are as follows:**

- **REQ\_LEFT\_ITEM**

  **Move left to an item.**

- **REQ\_RIGHT\_ITEM**

  **Move right to an item.**

- **REQ\_UP\_ITEM**

  **Move up to an item.**

- **REQ\_DOWN\_ITEM**

  **Move down to an item.**

- **REQ\_SCR\_ULINE**

  **Scroll up a line.**

- **REQ\_SCR\_DLINE**

  **Scroll down a line.**

- **REQ\_SCR\_DPAGE**

  **Scroll down a page.**

- **REQ\_SCR\_UPAGE**

  **Scroll up a page.**

- **REQ\_FIRST\_ITEM**

  **Move to the first item.**

- **REQ\_LAST\_ITEM**

  **Move to the last item.**

- **REQ\_NEXT\_ITEM**

  **Move to the next item.**

- **REQ\_PREV\_ITEM**

  **Move to the previous item.**

- **REQ\_TOGGLE\_ITEM**

  **Select/deselect an item.**

- **REQ\_CLEAR\_PATTERN**

  **Clear the menu pattern buffer.**

- **REQ\_BACK\_PATTERN**

  **Delete the previous character from the pattern buffer.**

- **REQ\_NEXT\_MATCH**

  **Move to the next item matching the pattern match.**

- **REQ\_PREV\_MATCH**

  **Move to the previous item matching the pattern match.**

**If the second argument is a printable character, the code appends** **it to the pattern buffer and attempts to move to the next item matching** **the new pattern.** **If there is no such match, menu\_driver returns** **E\_NO\_MATCH and deletes the appended character from the buffer.**

**If the second argument is one of the above pre-defined requests, the** **corresponding action is performed.**

### Mouse Handling

**If the second argument is the KEY\_MOUSE special key, the associated** **mouse event is translated into one of the above pre-defined requests.** **Currently only clicks in the user window (e.g., inside the menu display** **area or the decoration window) are handled.**

**If you click above the display region of the menu:**

- •

  **a REQ\_SCR\_ULINE is generated for a single click,**

- •

  **a REQ\_SCR\_UPAGE is generated for a double-click and**

- •

  **a REQ\_FIRST\_ITEM is generated for a triple-click.**

**If you click below the display region of the menu:**

- •

  **a REQ\_SCR\_DLINE is generated for a single click,**

- •

  **a REQ\_SCR\_DPAGE is generated for a double-click and**

- •

  **a REQ\_LAST\_ITEM is generated for a triple-click.**

**If you click at an item inside the display area of the menu:**

- •

  **the menu cursor is positioned to that item.**

- •

  **If you double-click an item a REQ\_TOGGLE\_ITEM** **is generated and E\_UNKNOWN\_COMMAND is returned.** **This return value makes sense,** **because a double click usually means that an item-specific action should** **be returned.** **It is exactly the purpose of this return value to signal that an** **application specific command should be executed.**

- •

  **If a translation** **into a request was done, menu\_driver returns the result of this request.**

**If you clicked outside the user window** **or the mouse event could not be translated** **into a menu request an E\_REQUEST\_DENIED is returned.**

### Application-defined Commands

**If the second argument is neither printable nor one of the above** **pre-defined menu requests or KEY\_MOUSE,** **the drive assumes it is an application-specific** **command and returns E\_UNKNOWN\_COMMAND.  Application-defined commands** **should be defined relative to MAX\_COMMAND, the maximum value of these** **pre-defined requests.**

## RETURN VALUE

**menu\_driver return one of the following error codes:**

- **E\_OK**

  **The routine succeeded.**

- **E\_SYSTEM\_ERROR**

  **System error occurred (see [errno(3)](/errno/3.md)).**

- **E\_BAD\_ARGUMENT**

  **Routine detected an incorrect or out-of-range argument.**

- **E\_BAD\_STATE**

  **Routine was called from an initialization or termination function.**

- **E\_NOT\_POSTED**

  **The menu has not been posted.**

- **E\_UNKNOWN\_COMMAND**

  **The menu driver code saw an unknown request code.**

- **E\_NO\_MATCH**

  **Character failed to match.**

- **E\_REQUEST\_DENIED**

  **The menu driver could not process the request.**

## PORTABILITY

**These routines emulate the System V menu library.** **They were not supported on** **Version 7 or BSD versions.** **The support for mouse events is** *ncurses* **specific.**

## AUTHORS

**Juergen Pfeifer.** **Manual pages and adaptation for new curses by Eric S. Raymond.**

## SEE ALSO

**curses(3X),** **getch(3X),** **menu(3X)**