My dad painted office windows and doors with gold leaf...Attorneys at Law...etc, so he worked with glass a lot. If you take a glass cutter wheel, and etch slowly a "T" at the endpoint of the crack, the relief in the stress will sometimes arrest the propagation. Say the crack runs three inches "west" across your window...start the glass cutter wheel about an inch below "south of" the current tip, and just"west" of it, and score it upwards slowly till you're about an inch "north" of it. That'll usually hold the event until you can repair it. The crack reaches the score line, and makes a perpendicular jaunt, terminating. Works in glass greenhouses where wind can cause stress fractures, and repairing is far more conveniently done in fairer weather. On a vehicle, you can't obstruct view, but elsewhere, tape strengthens the joint, too. ...and safety glass in vehicles makes the T less effective. pete.

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A third rate theory forbids
A second rate theory explains after the fact
A first rate theory predicts...A. Lomonosov