running the attached example and following the steps 1-4 causes the onChange event to be lost
1. open the popup
2. click inside the popup
3. directly click inside the textbox and change the value without clicking anywhere else
4. click the submit button
-> the label is not updated because the onChange event is not sent to the server

the reason is a missing onFocus event when clicking the textbox in step 3.
this can be verified using the additional textbox listening to onFocus

a workaround is calling focus() in a client side onClick listener