---
name: "XkbSetDebuggingFlags"
section: "3"
platform: "linux"
package: "libx11"
version: "1.8.14-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/XkbSetDebuggingFlags"
---

# XkbSetDebuggingFlags(3)

Change the values of any of the debug controls

## NAME

XkbSetDebuggingFlags - Change the values of any of the debug controls

## SYNOPSIS

**Bool XkbSetDebuggingFlags** **(Display \****display***,** **unsigned int** *mask***,** **unsigned int** *flags***,** **char \****msg***,** **unsigned int** *ctrls\_mask***,** **unsigned int** *ctrls***,** **unsigned int \****ret\_flags***,** **unsigned int \****ret\_ctrls***);**

## ARGUMENTS

- *display*

  connection to X server

- *mask*

  mask selecting debug output flags to change

- *flags*

  values for debug output flags selected by mask

- *msg*

  message to print right now

- *ctrls\_mask*

  mask selecting debug controls to change

- *ctrls*

  values for debug controls selected by ctrls\_mask

- *ret\_flags*

  resulting state of all debug output flags

- *ret\_ctrls*

  resulting state of all debug controls

## DESCRIPTION

The debugging aids are intended for use primarily by Xkb implementors and are optional in any implementation.

There are two bitmasks that may be used to control debugging. One bitmask controls the output of debugging information, and the other controls behavior. Both bitmasks are initially all zeros.

To change the values of any of the debug controls, use *XkbSetDebuggingFlags.*

*XkbSetDebuggingFlags* modifies the debug output flags as specified by *mask* and flags, modifies the debug controls flags as specified by *ctrls\_mask* and ctrls, prints the message *msg,* and backfills *ret\_flags* and *ret\_ctrls* with the resulting debug output and debug controls flags.

When bits are set in the debug output masks, *mask* and *flags,* Xkb prints debug information corresponding to each bit at appropriate points during its processing. The device to which the output is written is implementation-dependent, but is normally the same device to which X server error messages are directed; thus the bits that can be set in *mask* and *flags* is implementation-specific. To turn on a debug output selection, set the bit for the output in the *mask* parameter and set the corresponding bit in the *flags* parameter. To turn off event selection for an event, set the bit for the output in the *mask* parameter and do not set the corresponding bit in the *flags* parameter.

When bits are set in the debug controls masks, *ctrls\_mask* and *ctrls,* Xkb modifies its behavior according to each controls bit. *ctrls\_mask* and ctrls are related in the same way that *mask* and *flags* are. The valid controls bits are defined in Table 1.

| | | |
| --- | --- | --- |
| Table 1 Debug Control Masks |
| Debug Control Mask | Value | Meaning |
| XkbDF\_DisableLocks | (1 \<\< 0) | Disable actions that lock modifiers |

*XkbSetDebuggingFlags* returns True if successful and False otherwise. The only protocol error it may generate is BadAlloc, if for some reason it is unable to allocate storage.

*XkbSetDebuggingFlags* is intended for developer use and may be disabled in production X servers. If it is disabled, *XkbSetDebuggingFlags* has no effect and does not generate any protocol errors.

The message in *msg* is written immediately. The device to which it is written is implementation dependent but is normally the same device where X server error messages are directed.

## RETURN VALUES

- True

  The *XkbSetDebuggingFlags* function returns True when successful.

- False

  The *XkbSetDebuggingFlags* function returns False when not successful.

## DIAGNOSTICS

- **BadAlloc**

  Unable to allocate storage