rightmost column in Wrapped alignment not being rendered

Import the exampleFile_2_7 project and show the 'Spinach Feredoxin Structure' tab. Position 81 is right most when viewed in 2.11.5.0, but position 80 is shown in the 2.12 merge, and the rightmost margine spacing is noticeably larger to fill the gap. Also, mousing over to the right shows 'position 81' is accessible, and also selectable!

So - sometihing is subtly broken in 2.12's alignment layout & rendering code. This is (probably) also leading to the one outstanding test failure - which passes on OSX but fails on Linux.

java.lang.AssertionError: expected [39] but found [40]
at jalview.gui.SeqPanelTest.testFindMousePosition_wrapped_scales_longSequence(SeqPanelTest.java:920)