Is there a way to add 'id' attributes to the form elements in the UI Designer?
No there is no way to do this, if you want Bonita to add it then you will have to add it as a new idea here:
and I will support you on this. (ignore the bad post it's already been reported)
You could have a look at adding the ID after the page has loaded...as follows
Other than that the only other way is to replicate all the widgets you need ids for as Custom Widgets.
PS: I realize this isn't the answer you were looking for but as it answers your question, please mark as resolved.
Thanks for your response!
As per your suggestion I've created an "idea" http://community.bonitasoft.com/ideas/give-developers-ability-add-ids-fo...
I don't think creating custom widgets to replicate what's already available would be ideal. It seems we spend more time trying to come up with hacks or workarounds rather than do simple development.
A workaround suggested was to use 'css classes' in the UI designer to add a unique class name so that we can reference that element using that class name. Like , $('.unique-class-name')