It's too easy to accidentally click the "Submit" button when scheduling something with the calendar widget, such as an operation, and think that it's the correct action to take.  When nothing is actually selected/confirmed in the calendar widget, a blank value gets submitted as the schedule date.

A few options exist for consideration:
* Disable the button altogether when the calendar is open;
* Improve the appearance of the "Apply" button on the calendar as to be more intuitive that user should submit a date/time there;
* Overload the Schedule button to automatically apply any values that have been selected (but thus far not yet applied) in an open calendar.

It's entirely possible that much of this confusion can/will be mitigated when RHQ-1506 and RHQ-1507 have been fully taken into consideration.  Thus, we'll put this in the usability queue for future examination.