KaptainKrunch states it as legal in his guide on wizards (that can be ound here: http://paizo.com/threads/rzs2nvk1&page=1?Core-Wizard-Guide-An-Expansion -to-Treantmonks. While I tend to agree I think it is not beyond doubt by any means.
My Thinking goes like this:
It is clearly legal to take a full-round action and a swift action in the same turn. However, a spell with a casting time of 1 round is not simply a full-round action. Under casting time it states: “A spell that takes 1 round to cast is a full-round action. It comes into effect just before the beginning of your turn in the round after you began casting the spell. You then act normally after the spell is completed. […]When you begin a spell that takes 1 round or longer to cast, you must continue the concentration from the current round to just before your turn in the next round (at least). If you lose concentration before the casting is complete, you lose the spell.”
The wording regarding swift actions an casting spells as a swift action goes like this: “A spell with a casting time of 1 swift action doesn’t count against your normal limit of one spell per round. However, you may cast such a spell only once per round. Casting a
spell with a casting time of 1 swift action doesn’t provoke attacks of opportunity.” “A swift action consumes a very small amount of time, but represents a larger expenditure of effort than a free action. You can perform one swift action per turn without affecting your ability to perform other actions. In that regard, a swift action is like a free action. You can, however, perform only one single swift action per turn, regardless of what other actions you take. You can take a swift action anytime you would normally
be allowed to take a free action. Swift actions usually involve spellcasting, activating a feat, or the activation of magic items.”
As it states that “you can perform one swift action per turn without affecting your ability to perform other actions I have no doubts that you can use a quickened spell while casting a full round spell.
However, dimension door ends your turn (same for shift, which refers to dimension door in that respect). The wording goes like this: “After using this spell, you can’t take any other actions until your next turn.” Therefore it is necessary to decide if dimension door does end the ongoing casting of the full-round spell.
I would say no, as you actually cast the full-round spell during your turn and just have to maintain concentration until the beginning of your next turn. I would not rule that concentration to be an (separate) action. While I know that concentrating to maintain a spell is a standard action I do not think that this makes the “concentration part” of the casting of a full-round spell a separate action (that you would take outside your turn, when you clearly can not take any actions). Furthermore I think that the wording of dimension door should be read as “you can’t take any other new actions until your next turn “.