XSENDEXTENSIONEVENT(3)

💖 XSENDEXTENSIONEVENT 💖

okay bestie, welcome to the XSENDEXTENSIONEVENT page — that's section 3 of the manual, aka the library-functions zone, and today we're learning how to yeet input extension events at a client 🦋✨

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🌸 NAME 🌸

XSendExtensionEvent — send input extension events to a client 💌

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✨ SYNOPSIS ✨

#include <X11/extensions/XInput.h>

Status XSendExtensionEvent( Display *display,
                            XDevice *device,
                            Window destination,
                            Bool propagate,
                            int event_count,
                            XEventClass *event_list,
                            XEvent *event_send);

🎀 the arguments (read them, i'm begging) 🎀

• display — the connection to the X server. your lil phone line to the server, basically 📞
• device — which device the events are coming from, bestie 🎮
• destination — the window the event is getting sent to. you can pass a window id, PointerWindow, or InputFocus 🪟
• propagate — a Boolean value, so either True or False 🫶
• event_count — how many XEventClasses are chillin' in event_list 🔢
• event_list — the list of event selections we're working with 📋
• event_send — a pointer to the event that's getting sent 📨

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💅 DESCRIPTION 💅

The XSendExtensionEvent request figures out the destination window, decides which clients should get the specified events, and ignores any active grabs. periodt, no grabs allowed.

This request requires you to pass an event class list. For a discussion of the valid event class names, see XOpenDevice(3). This request uses the w argument to identify the destination window, like so:

• If w is PointerWindow, the destination window is the window that contains the pointer 🖱️
• If w is InputFocus and the focus window contains the pointer, the destination window is the window that contains the pointer; otherwise, the destination window is the focus window 🎯

To determine which clients should receive the specified events, XSendExtensionEvent uses the propagate argument as follows:

• If event_list is the empty set, the event is sent to the client that created the destination window. If that client no longer exists, no event is sent. (rip, the client ghosted 😭)
• If propagate is False, the event is sent to every client selecting on destination any of the event types specified by the event_list array.
• If propagate is True and no clients have selected on destination any of the events specified by the event_list array, the destination is replaced with the closest ancestor of destination for which some client has selected a type specified by the event-list array and for which no intervening window has that type in its do-not-propagate-mask. If no such window exists, or if the window is an ancestor of the focus window and InputFocus was originally specified as the destination, the event is not sent to any clients. Otherwise, the event is reported to every client selecting on the final destination any of the events specified in the event_list array.

okay so the event in the XEvent structure must be one of the events defined by the input extension (or a BadValue error results) so that the X server can correctly byte-swap the contents as necessary. no cap, pick a real one.

The contents of the event are otherwise unaltered and unchecked by the X server — except to force send_event to True in the forwarded event and to set the serial number in the event correctly. that's it, that's the whole glow-up the server gives it ✨

XSendExtensionEvent returns zero if the conversion to wire protocol format failed, and returns nonzero otherwise. XSendExtensionEvent can generate BadClass, BadDevice, BadValue, and BadWindow errors. 👑

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🚨 DIAGNOSTICS 🚨

• BadDevice — an invalid device was specified. The specified device does not exist or has not been opened by this client via XOpenInputDevice. This error may also occur if the specified device is the X keyboard or X pointer device. (the X keyboard and X pointer are lowkey off-limits 🙈)
• BadValue — some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error. 🔢
• BadWindow — a value for a Window argument does not name a defined window. (that window does not exist, bestie 💀)

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and that's the whole page, you ate it 💅✨ go forth and send some extension events, you absolute icon 🫶

this diva of a manpage is brought to you by the XSendExtensionEvent(3) crew, dated 05/18/2026 — remember the date, it's giving historic ⭐👑