要设置 enableSubmissionForm: false
否则chrome会报 Form submission canceled because the form is not connected" error
火狐更垃圾不报具体错误就是submit后居然调用succss，里面给出json decode错误
https://stackoverflow.com/questions/43000292/getting-form-submission-canceled-because-the-form-is-not-connected-error-in-ch
https://blog.csdn.net/jpzhu16/article/details/56919491
大概是modern默认为true,就不添加form到dom中(但我查看结构是有的啊)
classic没这么个毛病
enableSubmissionForm : Boolean
The submission form is generated but never added to the dom. It is a submittable version of your form panel, allowing for fields that are not simple textfields to be properly submitted to servers. It will also send values that are easier to parse with server side code.
If this is false we will attempt to subject the raw form inside the form panel.
Defaults to:
true