diff --git a/edit.lua b/edit.lua
index 1293610..cf4d3b8 100644
--- a/edit.lua
+++ b/edit.lua
@@ -1,7 +1,6 @@
 -- some constants people might like to tweak
 Text_color = {r=0, g=0, b=0}
 Cursor_color = {r=1, g=0, b=0}
-Focus_stroke_color = {r=1, g=0, b=0}  -- what mouse is hovering over
 Highlight_color = {r=0.7, g=0.7, b=0.9}  -- selected text
 
 Margin_top = 15
diff --git a/reference.md b/reference.md
index 0e3e53d..2c8b07c 100644
--- a/reference.md
+++ b/reference.md
@@ -231,6 +231,14 @@ locations in the widget are `cursor1` describing where text is inserted or
 deleted and `screen_top1` which specifies how far down the lines is currently
 visible on screen.
 
+Some constants that affect editor behavior:
+* `Margin_top`, `Margin_left`, `Margin_right` are integers in pixel units that
+  affect where the editor is drawn on window (it always extends to bottom of
+  window as needed)
+
+* Various color constants are represented as tables with r/g/b keys:
+  * `Text_color`, `Cursor_color`, `Highlight_color` for drawing text.
+
 ### clickable buttons
 
 There's a facility for rendering buttons and responding to events when they're