---
name: "xcb_query_tree"
section: "3"
platform: "linux"
package: "libxcb"
version: "1.17.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/xcb_query_tree"
---

# xcb\_query\_tree(3)

query the window tree

## NAME

xcb\_query\_tree - query the window tree

## SYNOPSIS

**#include \<xcb/xproto.h\>**

### Request function

xcb\_query\_tree\_cookie\_t **xcb\_query\_tree**(xcb\_connection\_t \**conn*, xcb\_window\_t *window*);

### Reply datastructure

```

typedef struct xcb_query_tree_reply_t {
    uint8_t      response_type;
    uint8_t      pad0;
    uint16_t     sequence;
    uint32_t     length;
    xcb_window_t root;
    xcb_window_t parent;
    uint16_t     children_len;
    uint8_t      pad1[14];
} xcb_query_tree_reply_t;
```

### Reply function

xcb\_query\_tree\_reply\_t \***xcb\_query\_tree\_reply**(xcb\_connection\_t \**conn*, xcb\_query\_tree\_cookie\_t *cookie*, xcb\_generic\_error\_t \*\**e*);

### Reply accessors

xcb\_window\_t \***xcb\_query\_tree\_children**(const xcb\_query\_tree\_request\_t \**reply*);

int **xcb\_query\_tree\_children\_length**(const xcb\_query\_tree\_reply\_t \**reply*);

xcb\_generic\_iterator\_t **xcb\_query\_tree\_children\_end**(const xcb\_query\_tree\_reply\_t \**reply*);\

## REQUEST ARGUMENTS

- *conn*

  The XCB connection to X11.

- *window*

  The *window* to query.

## REPLY FIELDS

- *response\_type*

  The type of this reply, in this case *XCB\_QUERY\_TREE*. This field is also present in the *xcb\_generic\_reply\_t* and can be used to tell replies apart from each other.

- *sequence*

  The sequence number of the last request processed by the X11 server.

- *length*

  The length of the reply, in words (a word is 4 bytes).

- *root*

  The root window of *window*.

- *parent*

  The parent window of *window*.

- *children\_len*

  The number of child windows.

## DESCRIPTION

Gets the root window ID, parent window ID and list of children windows for the specified *window*. The children are listed in bottom-to-top stacking order.

## RETURN VALUE

Returns an *xcb\_query\_tree\_cookie\_t*. Errors have to be handled when calling the reply function *xcb\_query\_tree\_reply*.

If you want to handle errors in the event loop instead, use *xcb\_query\_tree\_unchecked*. See **[xcb-requests(3)](/xcb-requests/3.md)** for details.

## ERRORS

This request does never generate any errors.

## EXAMPLE

```

/*
 * Displays the root, parent and children of the specified window.
 *
 */
void my_example(xcb_connection_t *conn, xcb_window_t window) {
    xcb_query_tree_cookie_t cookie;
    xcb_query_tree_reply_t *reply;
    cookie = xcb_query_tree(conn, window);
    if ((reply = xcb_query_tree_reply(conn, cookie, NULL))) {
        printf("root = 0x%08x\n", reply->root);
        printf("parent = 0x%08x\n", reply->parent);
        xcb_window_t *children = xcb_query_tree_children(reply);
        for (int i = 0; i < xcb_query_tree_children_length(reply); i++)
            printf("child window = 0x%08x\n", children[i]);
        free(reply);
    }
}
```

## SEE ALSO

[**xcb-requests**(3)](/xcb-requests/3.md), [**xcb-examples**(3)](/xcb-examples/3.md), [**xwininfo**(1)](/xwininfo/1.md)

## AUTHOR

Generated from xproto.xml. Contact xcb@lists.freedesktop.org for corrections and improvements.