This modification adds two separate settings. One for a vertical tab and one for a multiline tab in the settings dialog under TabBar. It also fixes a flickering issue I noticed where the tab control was being completely redrawn when it didn't need to. For a lot of the drawing their are hard coded numbers for drawing offsets. Please respects these as it took me forever to get it looking perfect in all the possible tab views.
Please see preference.rc.txt as it is NOT a diff, but rather instructions on adding two lines to the RC file.