If you use the Ctrl, Alt, or Shift key when clicking links to open them in a new tab or window, then I suggest you try the Click Modifiers extension for Firefox. The extension gives you a handful of behaviors that you can assign to these hotkeys when clicking a link. Click Modifiers lets you change the Ctrl, Alt, and Shift keys on Windows or the Command, Option, and Shift keys on OS X.
For example, I use the Command key when clicking links on my MacBook to open them in a new tab because it's faster than performing the two-finger click on the touchpad to call up the right-click menu. By default, holding the Command key down when clicking a link opens it in a new tab in the background. Click Modifiers would let me change this to opening the tab in a new tab in the foreground or in a new window or assigning the Option or Shift key to do this.
Click Modifiers does not require a restart, and it does not add a button to Firefox. To access its settings, you'll need to head to Firefox's extension and click the Preferences button for Click Modifiers. There, you'll find it offers the same options for each key. They are:
- Opens link in current window/tab
- Opens link in new window
- Opens link in new tab
- Opens link in new background tab
- Saves link
And for the mousers among us, there is an option to assign one of the above behaviors to your middle mouse button.
If you decide a modification you made isn't to your liking, you can easily revert back to the way things were before by selecting "Uses default action" for the key in question.