[Regression] Segfault when running two instances

[ModProg]

Describe the bug
Running wry twice it segfaults

Steps To Reproduce
cargo run --example hello_world & cargo run --example hello_world

Expected behavior
Two instances should start

LOG

(process:246998): Gtk-CRITICAL **: 09:57:30.630: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed

(process:246998): Gtk-CRITICAL **: 09:57:30.632: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed

(process:246998): Gtk-CRITICAL **: 09:57:30.632: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed
Wry has started!
[1]  + 246998 segmentation fault (core dumped)  cargo run --example hello_world

Platform and Versions (please complete the following information):
OS: Linux
Rustc: 1.53.0-nightly (42816d61e 2021-04-24) also on stable

Would you assign yourself to resolve this bug?

• Yes
• No

Additional context
This is a regressing, 0.8.0 works fine

[wusyong]

Thanks for the report!
Tested it and found this is caused by fixed application id introduced in v0.9
I'll make it None for now and maybe expose a method for users to set it.