1947 J-3 Cub sliding window advice

I hope my peers on the EAA forums can provide some advice. On my J-3 cub, I've had two incidents now where the left sliding window has popped out during a slip while the opposite door-window is open. Are there any tricks or tips to a permanent fix sans replacing the sliding window with a fixed, heavier thickness window? Apparently this is fairly common for I have read about similar incidents on other forums, yet I haven't found a reasonable solution. Thanks In advance for your free advice!

No, there is no "fix." Yes, it is a common Cub thing. Fly in trim when the door is open. Keep a replacement left window ready to install when it happens again. Sometime, it removes all the glass on the L side.
Bob