The topic says it all.
When you use an onDataChange event then it’s impossible to tab through your fields. When triggered the field loses it’s focus and the focus ends up in thin air.
This is a big annoyance for me because I need to force some calculations (because of the recent calculation changes) to calculate but now it forces my client to use the mouse to go to the next field.
In fact when you edit a field with an onDataChange method and you click on another field you have to click in it twice because the first time the focus ends up in thin air (see previous remarks).