General info :
 It's the standard wings connect command with a twist : if the connect operation resulted in one loop, it will allow you to slide this loop, with different options. It appears in the contextual edge menu.
 
  Installation & compatibility :
 download wpc_connect_s_98_04.zip here.

 Basics :
 For example, on a cube : select one edge ( whatever), hit G to select the ring, rmb to bring the menu, click on connect_s, drag the loop in position, confirm by left clicking, or cancel the command by right-click..
 Note that, just as all 'tweak-like' plugin, you can zoom while dragging, but it's not possible to rotate the camera while dragging (if doing so, the result will always be the same as standard connect).
 The distance is indicated in the status bar, left side, in % (see options below).
 

 Option : Operating Mode:
 There are 4 different mode within this plugin, you can check the actual mode on the right of the status bar. Note that you can switch operating modes during dragging, you'll just need to move the mouse slightly to see the change :
 just to allow comparison, here is the standard connect on the example's mesh :

 REL (shortcut : UP ARROW) : means relative; all the vertices are moving a distance which is proportional to the original length of the edge they're sliding on. This is the default mode. This acts precisely as was the plugin connect_and_slide.

  All others three mode, the distance moved is the same for all vertices in WU ( Wings Unit),
 LEFT (shortcut : LEFT ARROW) : the vertices are moved the same distance from the left adjacent loop; this will result in a loop that tends to have the same shape, and in some case have, that the left adjacent loop. The distance is measured from the left loop.

 RIGHT (shortcut : RIGHT ARROW) : the vertices are moved from the right adjacent loop. Distances are measured from the right loop.

 MID (shortcut : DOWN ARROW) : the starting position is each vertex at the middle of each cut edge ( as standard connect). From there the vertices are moved the same distance, on the left or on the right, as user choose. The distance is measured from this middle position.

 Lastly, please note that even if you slide a loop all the way down to another, this doesn't mean that the vertices have been welded. To check , take a cube, connect a ring of edges and slide the resulting loop 100% in REL (in this case all mode are equivalent , as all edges are of equal length); now smooth it, you'll get this :