I've had these annoying drip marks on window of my oven door for about a year. The cleaning cycle of the oven didn't take care of it nor did wiping the window. The drip was between two panes of glass. I gave up, UNTIL I saw the solution in Real Simple magazine.
You can see in this photo that I slid a spatula through the opening and between the panes of glass.
Cover a spatula with a damp cloth and insert between the glass panes and rub until marks disappear. You can see that I have removed part of the marks.
The door is back on the hinges and the window is free of the greasy streaks. I'm happy.