Display Unread Messages in Bold when in Vertical View
By default, unread messages in vertical view show a blue dot to the left of the message, but do not appear in a bold typeface. If you'd like messages to display in bold when using Vertical View, you can do so by changing a hidden preference in the Config Editor.
To do this,
- Open the Config Editor.
- Type in pb.thread_pane.vertical.bold_unread into the "Filter" textbox.
- Double-click on pb.thread_pane.vertical.bold_unread to change the value from false to true.