adapting 'pen trails capture' messages

objects.js

@@ -6207,7 +6207,7 @@ StageMorph.prototype.userMenu = function () {
     if (shiftClicked) {
         menu.addLine();
         menu.addItem(
-            "turn pen trails into new costume...",
+            ide.currentSprite instanceof SpriteMorph ?	"turn pen trails into new costume..." : "turn pen trails into new background...",
             function () {
                 var costume = new Costume(
                     myself.trailsCanvas,
@@ -6217,8 +6217,10 @@ StageMorph.prototype.userMenu = function () {
                 ide.currentSprite.wearCostume(costume);
                 ide.hasChangedMedia = true;
             },
-            'turn all pen trails and stamps\n' +
-                'into a new costume for the\ncurrently selected sprite',
+            ide.currentSprite instanceof SpriteMorph ? 'turn all pen trails and stamps\n' +
+                'into a new costume for the\ncurrently selected sprite' :
+				'turn all pen trails and stamps\n' +
+				'into a new background for the stage',
             new Color(100, 0, 0)
         );
     }