progress adding ability to change colour of triangle

functional-core/app/app-update.sml

@@ -412,7 +412,7 @@ struct
     | RESIZE_WINDOW {width, height} => resizeWindow (model, width, height)
     | UNDO_ACTION => undoAction model
     | REDO_ACTION => redoAction model
-    | KEY_G => toggleGraph model
+    | KEY_T => toggleGraph model
     | KEY_CTRL_S => getSaveTrianglesMsg model
     | KEY_CTRL_L => getLoadTrianglesMsg model
     | KEY_CTRL_E => getExportTrianglesMsg model