This window is used to simplify and speed up the adjustment of splines on head mesh. You may of course adjust without using this window by moving controls manually, but in that case the whole process will take too much time, so, read all information below carefully, understand how to simplify adjustment and use these methods in your BonyFace workflow.

Right Side / Separate Left Side - radiobuttons at top of the window define splines and controls this window works with: right side or left side. I recommend to start with default Right Side option and adjust right side, after that if your model is asymmetric then turn on Separate Sides in main window, switch to second option Separate Left Side in this window and adjust left side.

Some buttons near label Get edges by: are used to align controls by selected edges of the mesh. Select edges at first and then adjust current spline by selection. Selected edges must form a single line.
points Selects edges by picking two points: start point and end point. Press the button and click on a mesh (with 3D snap turned on by Endpoint) at two different vertices. If these vertices belong to a single edgeloop then edges between them will be selected
vertices Selects edges between two selected vertices of the mesh: start and end. Select two vertices and press this button. If these vertices belong to a single edgeloop then edges between them will be selected
These buttons work if closed edgeloop is selected, for example circular edgeloops in eyelid or mouth areas. Press top button to select only upper half of the edgeloop, press bot button to select lower half. This may be useful while adjustment of splines at top/bottom eyelid or top/bottom lip
Align current spline by selected edges Button aligns controls of current spline by selected edges immediately. Read below how to know which spline is current, but if Next checkbox is checked then script itself will change current spline, so when you aligned some spline it switches to next spline automatically
Dropdown list and buttons around it respond to browse through spline model. Current spline is highlighted in orange color, you can change it by selected another item in the list or press buttons with up/down arrows. All button selects all controls of current spline, 1-6 buttons select specific controls (numbers go from nose to temple) of current spline, buttons with forward/backward arrows select controls in order
Hide Current Spline Hide/Show current splne and its controls
Hide all splines and controls Hide/Show all splines and controls at current side of the head
Undo Last Operation Turn back to previous position of adjusted control(s)

    Two buttons near label Draw: align controls by painting on a mesh
  1. Line - press button and paint on model while holding left button of a mouse, controls of the current spline will be aligned by the resulting curve
  2. Point - press button and paint on model while holding left button of a mouse, selected control will be aligned by the first vertex of resulting curve (works only with single selected control)
    Other buttons in bottom-right area provide additional tools of alignment
  1. Specify - Move selected controls into nearest vertices of the mesh
  2. Stick - Move selected controls to the mesh parallel to world Y-axis ("glue" on the head)
  3. Put - Turns on mode of sequential displacement of selected controls to the mesh by click, to skip control use right-click, to finish and exit this mode use ESC button