Patrick,
I've set up the conditional formatting as described above, using a xdExtension function, and it works fine. The problem comes when I try to use the same expression in a Data Validation clause.
I placed a break point in function I'm calling with xdExtension and I tested that the return value was set to the correct value - although bizarrely the function is called twice each time a value changes within the repeating group.
However the actual data validation behaves erratically...
When the user selects a particular value from a repeating section, I want to evaluate a field and prevent submission if the field is blank, however what happens is:
When the form is opened the option is deselected and the field is empty, the validation warning is displayed and the form can't be submitted. If select the option, the validation warning goes away and the form can be submitted even though the field is blank (the opposite of what I want!).
I've played with the validation expression I'm using:
xdExtension:OtherApplicationSelected() = true
and it doesn't matter if I test for 'true' or 'false', the data validation behaves the same.
It's a pity I can't post a .jpg of my form and the validation condition - it'd be easier to show you what I'm trying to do. :)