Click on URL in email, open new tab in browser, BUT stay in same Thunderbird email

Question

There used to be a way to click on a link (URL) in an email that would open a new tab/window in the browser (Firefox), BUT stay in Thunderbird - similar to what Ctrl-Left-click does in Google search results in Firefox.
My work flow is usually to open several links, staying in Thunderbird and then when I'm done - go to Firefox to look at them all. E.g. I get a stackexchange weekly summary email, click on all the topics that look interesting and then, when I'm done selecting them, go look at them in Firefox.
I don't want to be forced to jump back and forth for every link, one at a time. This used to work.
Is there a preference or add-on that will do this - or anything else?

Answer 1

I'm not aware of any complete reference to all preferences that offer a full explanation of what each does, what the Value means and how to use in a problem-oriented fashion.
But the list below does help:
http://kb.mozillazine.org/Category:Preferences
http://kb.mozillazine.org/About:config
http://kb.mozillazine.org/About:config_entries
http://www-archive.mozilla.org/unix/customizing.html#ui
http://preferential.mozdev.org/preferences.html
there is also a postscript module used by eg: linux
http://kb.mozillazine.org/PostScript_Module
Margins are set up here:
File > Page Setup > Margins & header/Footer
or via File > Print Preview > Page Setup button
Helpful hints:
if you have Margins (millimeters)
and set eg: Bottom margin as 20.0
then look in config editor, you will see:
print.printer_XX.print_margin_bottom; Value = 0.787500023841858
This seemed odd at first. All Values in config were being converted to inches represented in a decimal format.
If you ever need to change the margins from millimeter to inches:
Print.printer_xx.print_paper_size_unit Value: = 1
Change the Value to 0 (zero) to get inches
If you change the Value to 0 for inches and then reopen:
File > Page Setup > Margins & header/Footer
you will see the Bottom margin has auto changed from 20.0 (mm) to 0.8 (inches rounded up), so although the display is different in File > Page Setup > Margins & header/Footer tab, the actual information in config preferences remains unchanged as it is saved in decimal inches format used by US as default.
if using millimeters then the paper size would be A4 210 x 297 mm.
Although looking in the config preferences it will say paper width 8.50 and paper height 11.00.
Usually, you can change the paper size when you select to Print and look in Print Properties. I'm in UK and using millimeters so get A4; the US uses Letter 8½ x 11 inches.
So I can see how it could be confusing to anyone using millimeters and then sees, what appears like wrong data in preferences.