Highlight Links That Will Open in a New Tab

First apply these settings in Iceweasel :

Edit > Preferences > Tabs
Open new windows in a new tab instead
Always show the tab bar
When I open a link in a new tab, switch to it immediately


Add these lines to userContent.css in ~/.mozilla/firefox/xxxxxxxx.default/chrome

/* Hilight links which will try to open in a new window */
/* This gives a grey background on the link, and also the "crosshair" moise pointer on hover */
:link:hover[target="_blank"], :visited:hover[target="_blank"],
:link:hover[target="_new"], :visited:hover[target="_new"] {
color: white !important;
background: grey !important;
cursor: crosshair;