I have a question, sorry for being silly, but could someone check or help. On the top of the computer on the menu bar where there is an apple, finder, go etc. when I first turn the iMac on the apple is black on top and lighter white-gray on bottom. If I open calendar, safari etc to full screen and make the menu and apple disappear, when I minimize and the menu bar comes back the apple is almost all black. The apple stays darker black, until I shutdown or restart then it's a lighter gray on bottom color until I maximize again. Could someone see if theirs is the same way. If not what kind if any problem does this represent???? Thanks for helping.