Mate lock screen is not working correctly

When the suspend is working, which is as far as I tested mostly one time after a reboot, there is a security issue with the lockscreen from mate. After resuming you can see the desktop for a very short time before the lockscreen with password protection is activated. With a camera it would be easily possible to capture the screen. This should be fixed. I think the lockscreen activation is to slow and it is not done completely before the system is already suspending and then activation is completed after resume.
This problem occurs not all the time, but mostly, when the system was under some load or paging when suspending.