Henning wrote:
ContentTop (A, B, C)
ContentBottom (A, B, C)
are NOT controlled via layout sliders ... Gantry adds the distribution for those automatically based on the width of mb.
SO nothing is missing.
Breadcrumb/drawer/fullwidth/analytics and debug don't have the gantry standard Gantry chrome and so they dont have the a, b, c, d, e and f options. They just don't need sliders ...
Hi Henning:
OK … I'm slightly disappointed that ContentTop & ContentBottom aren't controlled by sliders and are the "odd ones out" (of all the fields with multiple positions). 
Having the ability to adjust their widths (within the width supplied to Main Content) would be nice.