x11: internal window to send close backend event to

src/backend/x11/mod.rs

@@ -118,7 +118,10 @@ use x11rb::{
     protocol::{
         self as x11,
         dri3::ConnectionExt as _,
-        xproto::{ColormapAlloc, ConnectionExt, PixmapWrapper, VisualClass},
+        xproto::{
+            ColormapAlloc, ConnectionExt, CreateWindowAux, PixmapWrapper, VisualClass, WindowClass,
+            WindowWrapper,
+        },
         ErrorKind,
     },
     rust_connection::{ReplyError, RustConnection},
@@ -216,9 +219,28 @@ impl X11Backend {
 
         let atoms = Atoms::new(&*connection)?.reply()?;
 
+        // We need to give the X11Source a window we have created, we cannot send the close event to the root
+        // window (0). To handle this, we will create a window we never map or provide to users to the backend
+        // can be sent a message for shutdown.
+
+        let close_window = WindowWrapper::create_window(
+            &*connection,
+            x11rb::COPY_DEPTH_FROM_PARENT,
+            screen.root,
+            0,
+            0,
+            1,
+            1,
+            0,
+            WindowClass::INPUT_OUTPUT,
+            x11rb::COPY_FROM_PARENT,
+            &CreateWindowAux::new(),
+        )?
+        .into_window();
+
         let source = X11Source::new(
             connection.clone(),
-            0, // send the close request to something to ensure we can wake the reader thread for events.
+            close_window,
             atoms._SMITHAY_X11_BACKEND_CLOSE,
             logger.clone(),
         );