Trying to add an attachment to an email: 1. Click on the attachment icon on the toolbar. 2. The add attachment dialog/file manager appears. 3. It is automatically opening to my downloads folder 4. I try to change to documents, or any other folder under places. While I can highlight another folder, the right pane is dead. My OS is Linux Mint 17.3; the kernal is Linux 3.19.0; TBird is v.56.6.0 64 bit. I've tried in safe mode with all addons disabled, but same result. My current active addons are Lightning, Theme Font and Size Changer. Appearance is simply the default theme.