Typing is jerky in El Capitan

Typing in Rapidweaver 6 edit mode is jerky (type moves up and down) after I upgraded to El Capitan 10.11.3. This problem was not there in Yosemite and it’s not happening in other programs. Anyone else with this problem? I’ve restarted my MacBook Pro numerous times and still having this problem. It seems to be the same issue in different themes. I’m running RW6.3.7, the latest version.

Doesn’t happen to me in 10.11.3.