3 files changed, 36 insertions, 12 deletions

diff --git a/src/clients/client.rs b/src/clients/client.rs
index a7b1a8d..3648f0c 100644
--- a/src/clients/client.rs
+++ b/src/clients/client.rs
@@ -3,7 +3,7 @@ use xcb::{
         ChangeProperty, ChangeWindowAttributes, ConfigWindow, ConfigureNotifyEvent,
         ConfigureWindow, Cw, EventMask, MapWindow, SendEvent, SendEventDest, Window,
     },
-    Xid,
+    VoidCookie, VoidCookieChecked, Xid,
 };
 
 use crate::{config::BORDER_WIDTH, conn_info::Connection};
@@ -125,11 +125,15 @@ impl Client {
 
     /// Set the event mask for this window
     /// This function does not check for success, so `conn.flush()` should be called after.
-    pub fn set_event_mask(&self, conn: &Connection<'_>, event_mask: EventMask) {
-        conn.send_request(&ChangeWindowAttributes {
+    pub fn set_event_mask(
+        &self,
+        conn: &Connection<'_>,
+        event_mask: EventMask,
+    ) -> VoidCookieChecked {
+        conn.send_request_checked(&ChangeWindowAttributes {
             window: self.window(),
             value_list: &[Cw::EventMask(event_mask)],
-        });
+        })
     }
 
     /// Sync the non-geometry related properties with EWMH hints
@@ -150,14 +154,14 @@ impl Client {
     }
 
     /// Set the given window as withdrawn / not withdrawn.
-    pub fn set_withdrawn(&self, conn: &Connection<'_>, withdrawn: bool) {
-        conn.send_request(&ChangeProperty {
+    pub fn set_withdrawn(&self, conn: &Connection<'_>, withdrawn: bool) -> VoidCookieChecked {
+        conn.send_request_checked(&ChangeProperty {
             mode: xcb::x::PropMode::Replace,
             window: self.window,
             property: conn.atoms.wm_state,
             r#type: conn.atoms.wm_state,
-            data: &[u8::from(!withdrawn), 0_u8],
-        });
+            data: &[u32::from(!withdrawn), 0_u32],
+        })
     }
 
     pub fn set_urgent(&mut self, urgent: bool) {
diff --git a/src/clients/mod.rs b/src/clients/mod.rs
index d07de74..70e3798 100644
--- a/src/clients/mod.rs
+++ b/src/clients/mod.rs
@@ -94,7 +94,9 @@ impl WM<'_> {
     pub(crate) fn handle_unmap_notify(&mut self, e: &UnmapNotifyEvent) -> Result<()> {
         if let Some(c) = self.clients.find_client_mut(e.window()) {
             if e.is_from_send_event() {
-                c.set_withdrawn(&self.conn, true);
+                let cookie = c.set_withdrawn(&self.conn, true);
+                // The above may fail if the window has already been destroyed - just discard the error here.
+                let _ = self.conn.check_request(cookie);
             } else {
                 self.clients.unmanage(&self.conn, e.window(), false);
             }
@@ -237,9 +239,12 @@ impl ClientState {
         let c = self.mons[mon].clients.remove(i);
 
         if !already_destroyed {
-            c.set_event_mask(conn, EventMask::empty());
+            c.set_event_mask(conn, EventMask::NO_EVENT);
             // TODO: Ungrab button
-            c.set_withdrawn(conn, true);
+            let cookie = c.set_withdrawn(conn, true);
+
+            // If any of the above requests fail, it's just a race condition and the window is already destroyed, so discard the error here.
+            let _ = conn.check_request(cookie);
         }
         self.rearrange(conn);
     }
diff --git a/src/conn_info/mod.rs b/src/conn_info/mod.rs
index 1981938..183f691 100644
--- a/src/conn_info/mod.rs
+++ b/src/conn_info/mod.rs
@@ -4,7 +4,7 @@ use xcb::{
         self, ChangeProperty, ChangeWindowAttributes, CreateWindow, DeleteProperty, DestroyWindow,
         Window, WindowClass,
     },
-    Connection as RawConnection, Cookie,
+    Connection as RawConnection, Cookie, VoidCookieChecked,
 };
 
 mod atoms;
@@ -190,6 +190,16 @@ impl<'a> Connection<'a> {
         cookie
     }
 
+    /// Delegate for [`RawConnection::send_request_checked`]
+    pub fn send_request_checked<R>(&self, req: &R) -> VoidCookieChecked
+    where
+        R: xcb::RequestWithoutReply + Debug,
+    {
+        let cookie = self.conn.send_request_checked(req);
+        debug_req!(req, cookie);
+        cookie
+    }
+
     /// Delegate for [`RawConnection::send_and_check_request`]
     pub fn send_and_check_request<R>(&self, req: &R) -> Result<()>
     where
@@ -199,6 +209,11 @@ impl<'a> Connection<'a> {
         self.conn.send_and_check_request(req).map_err(Into::into)
     }
 
+    /// Delegate for [`RawConnection::check_request`]
+    pub fn check_request(&self, c: VoidCookieChecked) -> Result<()> {
+        self.conn.check_request(c).map_err(Into::into)
+    }
+
     /// Delegate for [`RawConnection::flush`]
     pub fn flush(&self) -> Result<()> {
         self.conn.flush().map_err(Into::into)