I have a strange issue with Firefox 21.0 and Flash 11.7.700.202 on Windows 7: the game appears to be partially zoomed in (missing right and bottom parts).
If use Show All from the Flash contextual menu, the display is not zoomed out but the mouse pointer does get an offset that seems consistent with the missing parts of the display.
I have the same issue on From the Black, but not Arkea. On Diamon Hollow II, I have the zoom issue at startup but Show All fixes it correctly.
I have noticed this on other games so probably it's not just you.
Great and fun game. Is is true the controls can occasionally be frustrating (e.g. jumping up the stairs in level 22 is an assured way of getting stuck in a wall hang when you'd just expect to fall down the wall), but the deliciously inventive and sadistic level designs and the well-adjusted difficulty quite makes up for that.