Slider with negative range values not rendered correctly in VAqua4

Just noticed (while on hmmer branch) that WsParam sliders with negative range (e.g. TCoffee Cosmetic Penalty) are broken on 2.10.4 branch and develop (ok on 2.10.3). The slider does not display its position correctly, either while dragging, or on update from the value text field.
I had thought this was an artefact of changes on the Hmmer branch, but it appears not.
It is only a cosmetic problem - the value is correct in the text field and correctly passed to the invoked service.