Seems that the stacked chart in multidemo zooms correctly here (Laz trunk, fpc 2.6.4, Win). Please be more specific.
Hi, the effect is easier seen if percentage = true,
the sum should be always 100% in the correct case.
The bottom stack segment uses data range [FLoBound, FUpBound],
the upper segments use data range [AStart, AEnd], this is not compatible,
leads to wrong sums (totals) - a single sum uses different data indices,
but should use the same index.