This isn’t my screenshot, but this is what is happening in Photoshop CS6 after updating to Yosemite, the top of the open dialog gets chopped off. We’ve tested and this only happens when the second monitor is plugged in. We’ve adjusted the resolution of the second display and switched it back again which works to resolve it, but once you close Photoshop it returns to the broken dialog behaviour.
This Apple discussion is the best discussion I’ve found but doesn’t have any suggestions outside of the resolution one we found.
Same problem here. Unplug and plugin again helps (display port). After that the photoshop dialogs are complete visible (main system dialog: save, open…) – but the order of photoshops internal windows (layers…) are broken.