How to remove the column headers in Thunderbird's thread pane

The thread pane in Thunderbird is the part of the Thunderbird window that lists the contents of the selected folder, usually emails or email threads:



You can sort emails by sender, date, subject, or any of the other columns by clicking on the column headers. The downside is that when you like your emails threaded and accidentally click on a column header, you have to go to the View menu to turn threading back on because clicking on a column header turns it off. If you want to avoid this and also want to save some space (column headers have no use other than to change the sorting, since it is usually obvious what the sender and subject and date is), you can remove the column headers with two CSS rules in the userChrome.css file:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
/* set default namespace to XUL */

#threadTree treecols {
   height: 0px !important;
}

#threadTree treecolpicker {
   display: none !important;
}

The userChrome.css file must be placed in the chrome subdirectory in your Thunderbird profile directory. You may have to create the chrome directory if it does not exist.