There are so many funny quirks in SSIS 2012 that I have to list them, to save other people from the misery.

• If you want to move items to one direction, make sure you "grab" the opposite side.  For example, you want a whole bunch of data flows to move up, select them all and grab the lowest item.
• When you drag the arrow to connect Precendence Constraint, make sure you drop it on the area of target that has no text, otherwise, it thinks you want to edit the text and change the target item layout