diff --git a/dotscape b/dotscape
index 6755356..d60ade2 100755
Binary files a/dotscape and b/dotscape differ
diff --git a/ffi/glfw-input.c b/ffi/glfw-input.c
index 6da5b7d..b95df23 100644
--- a/ffi/glfw-input.c
+++ b/ffi/glfw-input.c
@@ -22,6 +22,7 @@ int KEY_O = GLFW_KEY_O;
 int KEY_A = GLFW_KEY_A;
 int KEY_W = GLFW_KEY_W;
 int KEY_H = GLFW_KEY_H;
+int KEY_C = GLFW_KEY_C;
 
 int KEY_ENTER = GLFW_KEY_ENTER;
 int KEY_SPACE = GLFW_KEY_SPACE;
diff --git a/ffi/glfw-input.sml b/ffi/glfw-input.sml
index fe604e4..24c2662 100644
--- a/ffi/glfw-input.sml
+++ b/ffi/glfw-input.sml
@@ -37,6 +37,8 @@ struct
     _symbol "KEY_G" public : ( unit -> int ) * ( int -> unit );
   val (KEY_B, _) =
     _symbol "KEY_B" public : ( unit -> int ) * ( int -> unit );
+  val (KEY_C, _) =
+    _symbol "KEY_C" public : ( unit -> int ) * ( int -> unit );
 
   val (KEY_T, _) =
     _symbol "KEY_T" public : ( unit -> int ) * ( int -> unit );
diff --git a/imperative-shell/file-thread.sml b/imperative-shell/file-thread.sml
index c36a0eb..a0a97b3 100644
--- a/imperative-shell/file-thread.sml
+++ b/imperative-shell/file-thread.sml
@@ -11,6 +11,7 @@ struct
   val structureName = "Green"
   val filename = "green.dsc"
   val exportFilename = "green.sml"
+  val collisionFilename = "green-collisions.sml"
 
   fun loadIO (io, str) =
     case TextIO.inputLine io of
@@ -33,18 +34,10 @@ struct
       | NONE => ()
     end
 
-  fun saveSquares squaresString =
+  fun saveString (filename, toSaveString) =
     let
       val io = TextIO.openOut filename
-      val () = TextIO.output (io, squaresString)
-    in
-      TextIO.closeOut io
-    end
-
-  fun exportSquares squaresString =
-    let
-      val io = TextIO.openOut exportFilename
-      val () = TextIO.output (io, squaresString)
+      val () = TextIO.output (io, toSaveString)
     in
       TextIO.closeOut io
     end
@@ -83,9 +76,10 @@ struct
     let
       val _ =
         case Mailbox.recv fileMailbox of
-          SAVE_SQUARES str => saveSquares str
+          SAVE_SQUARES str => saveString (filename, str)
+        | EXPORT_SQUARES str => saveString (exportFilename, str)
+        | EXPORT_COLLISIONS str => saveString (collisionFilename, str)
         | LOAD_SQUARES => loadSquares (filename, inputMailbox)
-        | EXPORT_SQUARES str => exportSquares str
         | LOAD_FILES path => loadFiles (path, inputMailbox)
         | SELECT_PATH path => selectPath (path, inputMailbox)
     in
diff --git a/imperative-shell/input-callbacks.sml b/imperative-shell/input-callbacks.sml
index c28d8cf..b75b82d 100644
--- a/imperative-shell/input-callbacks.sml
+++ b/imperative-shell/input-callbacks.sml
@@ -68,6 +68,11 @@ struct
       key = Input.KEY_E () andalso action = Input.PRESS () andalso mods = 0x002
     then
       Mailbox.send (mailbox, KEY_CTRL_E)
+    else if
+      (* ctrl-c *)
+      key = Input.KEY_C () andalso action = Input.PRESS () andalso mods = 0x002
+    then
+      Mailbox.send (mailbox, KEY_CTRL_C)
     else if
       key = Input.KEY_A () andalso action = Input.PRESS () andalso mods = 0
     then