Panic when using optirun and typing dead keys

thread 'main' panicked at 'attempt to subtract with overflow', /user/winit/src/platform/linux/x11/mod.rs:453:35
note: Run with `RUST_BACKTRACE=1` for a backtrace.
thread 'main' panicked at 'Failed to call XInternAtom (WM_PROTOCOLS): XError { description: "BadValue (integer parameter out of range for operation)", error_code: 2, request_code: 101, minor_code: 0 }', libcore/result.rs:945:5
stack backtrace:
   0:     0x55c1da1bda4b - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::h89ba7da7562701ab
                               at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1:     0x55c1da1c2ac0 - std::sys_common::backtrace::print::h6c31ad9817780cde
                               at libstd/sys_common/backtrace.rs:71
                               at libstd/sys_common/backtrace.rs:59
   2:     0x55c1da1ba16d - std::panicking::default_hook::{{closure}}::h2058dd93a82247f5
                               at libstd/panicking.rs:207
   3:     0x55c1da1b9ecb - std::panicking::default_hook::h679f309f083c9814
                               at libstd/panicking.rs:223
   4:     0x55c1da1ba5bf - std::panicking::rust_panic_with_hook::hf996e11af0921186
                               at libstd/panicking.rs:402
   5:     0x55c1da1ba3e2 - std::panicking::begin_panic_fmt::h8164d62b26e4856a
                               at libstd/panicking.rs:349
   6:     0x55c1da1ba312 - rust_begin_unwind
                               at libstd/panicking.rs:325
   7:     0x55c1da201430 - core::panicking::panic_fmt::hdbf1954249c01b91
                               at libcore/panicking.rs:72
   8:     0x55c1da0d5b77 - core::result::unwrap_failed::h31ff2f70a7055851
                               at /checkout/src/libcore/macros.rs:26
   9:     0x55c1da0d429b - <core::result::Result<T, E>>::expect::h6409ca11a4445996
                               at /checkout/src/libcore/result.rs:809
  10:     0x55c1da09707f - <winit::platform::platform::x11::Window as core::ops::drop::Drop>::drop::h2ff265fd9c5889fb
                               at src/platform/linux/x11/mod.rs:1087
  11:     0x55c1da04bac4 - core::ptr::drop_in_place::h3a2f256af65c530f
                               at /checkout/src/libcore/ptr.rs:59
  12:     0x55c1da04b72f - core::ptr::drop_in_place::h1c4983e117d6cf94
                               at /checkout/src/libcore/ptr.rs:59
  13:     0x55c1da04cb34 - core::ptr::drop_in_place::h9fb6a3aefef6e214
                               at /checkout/src/libcore/ptr.rs:59
  14:     0x55c1da0593c7 - xim::main::ha55699d7099b253c
                               at examples/xim.rs:34
  15:     0x55c1da0543a1 - std::rt::lang_start::{{closure}}::ha4ff232e21bac6fb
                               at /checkout/src/libstd/rt.rs:74
  16:     0x55c1da1ba277 - std::panicking::try::do_call::hf0fdbf659d7b57b7
                               at libstd/rt.rs:59
                               at libstd/panicking.rs:306
  17:     0x55c1da1c9c1e - __rust_maybe_catch_panic
                               at libpanic_unwind/lib.rs:102
  18:     0x55c1da1b7cc5 - std::rt::lang_start_internal::hc1351a73a73f54f6
                               at libstd/panicking.rs:285
                               at libstd/panic.rs:361
                               at libstd/rt.rs:58
  19:     0x55c1da054381 - std::rt::lang_start::hc4156819566d16cc
                               at /checkout/src/libstd/rt.rs:74
  20:     0x55c1da05943d - main
  21:     0x7f427b478f49 - __libc_start_main
  22:     0x55c1da047259 - _start
  23:                0x0 - <unknown>
thread panicked while panicking. aborting.
fish: './target/debug/examples/xim' terminated by signal SIGILL (Illegal instruction)

This may be caused by https://github.com/tomaka/winit/pull/297.

Reproduce the failure with optirun and dead-key input using examples/xim.rs, then inspect src/platform/linux/x11/mod.rs around line 453 and the Window drop path around line 1087. Compare the behavior with the referenced tomaka/winit pull request 297. Done means the xim example no longer panics or aborts in this scenario.