Thanks for the feedback:
> 1. When I drag an UI control into a grid cell, the UI control's label and the UI control itself are top down aligned. How to make both aligned at the same row (side by side). I could only figure out the way to do this by using bootstrap CSS.
That's correct, there is no option but working with CSS to change that right now. We have an RFE for it:
https://github.com/orbeon/orbeon-forms/issues/2865> 2. When we started to customize the form with CSS more & more due to the form builder limitation, the form designer no longer show the exact form output. This trouble us as we need to test/publish the form to view actual output which defeat the purpose of WYSIWYG editor.
You might be able to add CSS to Form Builder to apply your customizations there as well.
> 3. for the time component, is there any option to prefix zero in front of selected hour?
See the answer on Stack Overflow:
http://stackoverflow.com/questions/39218326/orbeon-documentation-for-oxf-xforms-format-input-time-Erik