Sm0knGun:
I am using Windows 10 and the current version of Firefox, and Adobe Shockwave Flash.
Sometimes I am unable to type in the chat.
I have found a work around. If you minimize the window, and bring it back up, it allows you to type again.
I can replicate this bug.
I use the same set-up as you do (FF Quantum Ver 58.0.1? ) and play the game in WGT's own full size screen mode - via the game client icon - with a pretty good meter.
I've not been able to chat, other than returning to the default screen size to do so, for long enough. The meter is horrendous and the game unplayable when I do.
Always have to remind myself to return to full screen mode before hitting a shot during multi-player games.
I'll try as you suggest next time I get the opportunity.
👍