Merge pull request #446 from zmike/xwindow-upstream

implement get_platform_window() return for X11

src/api/x11/mod.rs

@@ -705,7 +705,7 @@ impl Window {
     }
 
     pub fn platform_window(&self) -> *mut libc::c_void {
-        unimplemented!()
+        self.x.window as *mut libc::c_void
     }