A number of buttons do not seem to work, intermittently. • Reply, Reply, Forward • opening/closing messages in conversation view • download attachments I'm a long time thunderbird user. I've noticed this issue since upgrading to version 68. I'm currently using 68.2.0 (64-bit) and the issue still persists. Mac OSX 10.14.6. I have multiple email accounts set up in Thunderbird and it happens to all of them, so I don't thinks it's related to a single mailserver. I'm not sure what triggers the problem or what fixes it. Using keyboard shortcuts is my way around the issue when this happens.