Free plugin developed by the OxyPowerPack team. OXY Re-Login Window presents a login window right inside Oxygen Builder when the WordPress session expires, to avoid losing your work because of the infamous Oxygen "Error 200" while saving.
We said it when we initially developed it for OxyPowerPack, this feature should be part of Oxygen Builder. But until that happens, better grab this helper plugin.
You can download it from the WordPress plugin repository.