To the first question, have a look here:
http://kmeleonbrowser.org/forum/read.php?3,139534,139677,page=1#msg-139654
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guest
Speaking of, how would one change the background color of blank tabs?
For this, if I'm not wrong the easy way was removed in latest versions form the classic GUI and from the new about:preferences was buggy.
But you can type about:config in the url bar and then change this preference to the HEX color of your preference:
browser.display.background_color
You can choose a color code from here:
http://www.colorpicker.com/