Users love to provide their input or adjust settings as easy as possible
Start with collapsed options? > Choose date of next month > Get jumping interface
It’s really fundamental, that you do not change your interface layout regarding the position of input fields or check marks, while your users try to edit these. It will absolutely confuse and sometimes tease them. If there is e.g. a day marked „3“ like in this case in the calendar of OS X, and the users tries to choose this very day „3“, why should the interface jump to „31“ after a click? Just ask yourself if this result makes sense in case someone wants to choose „3“ and you know where to go. At the moment it’s like a small jump and run: Come on, try to hit the „3“!
You should always think about a fluid, smooth workflow, and good UX based design avoids jumping elements.
Besides: if there is a kind of editing mode in your interface and this editing panel is quite small,