Not exactly a bug, but a problem nonetheless. Galapagos treats sliders not as floating point values in some floating point domain, but as integers representing indices. Index=0 is the lowest value the slider can assume. Index=1 is the next value up, and so on. However when the total number of distinct values exceeds some large number (a million, I think, I’d have to check) it starts taking larger steps.
It’s a bug by design if you will, the steps could have been smaller (and indeed they will be in GH2, my new slider code supports a maximum of long.MaxValue distinct indices).
One way around this limitation now is to use two sliders to create a single number. Have one slider A control the major spacing, then add a second slider B for making tiny adjustments to that one value. Ie. the final value (assuming both slider are in the (0,1) range) would be A + B/100000