We’ve added a design option to set the click behaviour of the modal backdrop. You can now choose whether or not a click on the half transparent backdrop should close the survey or keep it open.
This new option is related to our latest update which allows you to hide or show the close button of a survey. It is currently only available for web-app surveys, but we are already working adding this option to surveys powered by our Mobile-SDKs.
You can find this new option in the Design tab in the survey editor.