tweak to slider function

[bpedit]

This is quite subtle but I think would add to workflow efficiency. 

 

When the triangular down arrow is selected on one of the parameter boxes, Opacity or Flow for example, the slider appears below the box. But the mouse must be dragged down to the slider to operate it. How about, once the slider appears, simply allowing the user to move the mouse left or right without first having to move it down over the slider itself. This would only operate this way, of course, if the user kept the left mouse button depressed after opening the slider.

[retrograde]

Good idea, I have noticed the workflow currently is a little bumpy...