A vehicle door is disclosed that has a movable window and a window regulator including a regulator rail and a regulator slider slidably mounted on the regulator rail and engaging the window for movement between a closed position and a fully open position. The door also has a window down stop stabilizer assembly including a position detecting assembly that detects when the window is in the fully open position, a bumper movable between a first position spaced from the window and a second position in contact with the window, and a bumper actuator that moves the bumper into and out of contact with the window. When the window is in the fully open position, the bumper actuator will move the bumper into the second position and when the window is not in the fully open position, the bumper actuator will move the bumper into the first position.