Use regular X11 rather than XFIXES to hide cursor

The semantics of the XFIXES cursor hide deal are annoying and make
things harder.

util/src/lib.rs

@@ -32,6 +32,20 @@ pub fn create_atom(conn: &xcb::Connection, name: &[u8]) -> xcb::Result<x::Atom>
     Ok(conn.wait_for_reply(cookie)?.atom())
 }
 
+pub fn destroy_pixmap(conn: &xcb::Connection, pixmap: x::Pixmap) -> xcb::Result<()> {
+    conn.send_and_check_request(&x::FreePixmap {
+        pixmap,
+    })?;
+    Ok(())
+}
+
+pub fn destroy_cursor(conn: &xcb::Connection, cursor: x::Cursor) -> xcb::Result<()> {
+    conn.send_and_check_request(&x::FreeCursor {
+        cursor,
+    })?;
+    Ok(())
+}
+
 pub fn destroy_gc(conn: &xcb::Connection, gc: x::Gcontext) -> xcb::Result<()> {
     conn.send_and_check_request(&x::FreeGc {
         gc,