Safari and Weebly editor

Has anyone had their Macs freeze up when they have the Weebly editor opened in a tab?

I've had to reset my Mac so many times in the past month, it's unbelievable. Often multiple times per day, and I finally figured out that it was when I had the Weebly editor opened. Not while using it - it's working great. But if I do anything else with the editor opened in a tab in the background, the computer will eventually freeze. The mouse pointer still moves, music or video streaming to an ATV still work in the background, but I can't move screens (I'm in fullscreen mode for all my apps), go into Mission Control, or anything else. Nothing works except reboot.

I decided to use Firefox instead, and all is well, no freezing up. So it's a specific issue with Safari and Weebly.

Since Safari doesn't crash, there is no crash log to send to Apple... How do I let them know about this issue?

Thanks!