I'm not sure what you mean...
TestButtons pos(46,2), channel("main-"), namespace("test")?
It's not about the value and defaults, it's just about visually where the tracker around the rslider would get drawn. I'll try to explain it better; here goes:
Currently if I do an
rslider with range(-1,1,0) the tracker will already be drawn from -1 to 0... or to whatever other value is selected. In other words, it's trackfrom(-1) by default.
If it were
rslider range(-1,1,0), trackfrom(0) then by default no tracker would be visible at 0, but if you rotate the slider down to -.5 the tracker appears from 0 to -.5. The tracker would always be drawn from 0 to whatever the current value, allowing you to create "symmetrical" trackers around the rslider similar to how the tracker on a vslider with both negative and positive range works.