First things first, have you created issues in the issue queues for these two modules? Chances are, the module maintainers will never see this post. Brian Eric Schaefer wrote:
Hi List,
the scheduler module uses date_popup for letting the user choose date and time for scheduled publishing of nodes, if it is installed. This causes a problem with the multistep module. With this module you can divide the node form into multiple steps like a "node wizard". date_popup transforms its two fields (date and time) into one field during validation (?) since the date_popup widget is virtually one field. If the scheduler field group is not part of the first multistep step then there has not been any validation for the scheduler/date_popup fields and therefore the publish_on field is still an array of two (empty) values instead of a single value. This confuses the schedulers validation logic, because it expects either an empty string or a propperly formatted string but not an array. To fix this I could check if it is an array and let it pass on validation. That would be rather easy and straitforward. But I do not like the idea of littering scheduler with code that circumvents problems with a non-core module that is not even used by scheduler itself. This would also introduce a nasty dependency on multisteps (form handling) behaviour. That would be fine, if scheduler did actually use multistep functionality (as it is using date_popups functionality), but it does not. I do not like that and I don't think this is a good thing to do.
What do you think. What should I do? How can this problem be resolved in a nice and clean way?
Regards, Eric