[Inkscape-user] filter parameters?

(using 0.47 nightly from a couple days ago, Ubuntu Linux)

How does one affect parameters for one of the pre-defined filters in the "Filter" pull-down menu? The Inkscape "Help" chapter about Filters bears little resemblance to the actual application; at least, it's certainly hard for me to tell what it's talking about when I look at what the application actually shows me. When I try to use any of the filters, I get a brief, blank pop-up dialog that shortly disappears, and then the filter takes effect with some canned parameters. I have to assume that the filters are actually configurable, but for the life of me I can't see how one does the configuration.