kill drag space

userChrome.css

/*
Create a userChrome.css file by finding your Firefox profile,
making a directory called chrome and in it, a file called userChrome.css inside that. 
Pasting this CSS and restarting Firefox will kill the left drag strip
*/

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

.titlebar-placeholder[type="pre-tabs"] {
  width: 2px !important;
}