* Fix string concatenation for _( "Unit" ) + wxT( " " ). This failed
compiling against wxWidgets 2.8 (thanks Cirilo Bernardo ).
* Base the indentation on a measured observation with explanation
(98%-ile of name-length found in library). The previously chosen 24
character indentation was too wide for most.
* Don't use a #define spilling into the global namespace, but use
a locally defined constant for COLUMN_DESCR_POS.
* Allow to select units in components that have more than one right in the
component chooser dialog.
* Keep chosen unit in history.
* Show preview of current component unit as thumbnail image next to the
description box.
* Fixes lp:1280567
* make some more fields 'const' that can.
* Instead of previous/next _visible_ element, Go through
previous and next element. Otherwise the cursor stops moving
if the item is only partially visible.