why the textarea sometimes hidden?

hi

I started to use CodeMirror few days. It is weird that, the textarea showing the
text being edited, got hidden once a while. Why is that happening? Did I put
some wrong parameter? or is it a known bug? I use Chrome to view the element.
The textarea does exist, but it becomes style="… display: none…" I did not put
it ! What happened! Why CodeMirror did it?

I appreciate any help!

I kind of walk around the issue. It looks like conflict with bootstrap.
Hope this helps anyone else.

fromTextArea, by design, always hides the textarea it is called on, not sometimes.

I see. I am really new to use CodeMirror. Thank you!