allow optional callback function for cancel button in checkAttached

package.json

@@ -76,7 +76,7 @@
         "c9.ide.find": "#a2dfc3e306",
         "c9.ide.find.infiles": "#488db22ee1",
         "c9.ide.find.replace": "#47a84af707",
-        "c9.ide.run.debug": "#651451a7c2",
+        "c9.ide.run.debug": "#fea509d749",
         "c9.automate": "#47e2c429c9",
         "c9.ide.ace.emmet": "#6dc4585e02",
         "c9.ide.ace.gotoline": "#d33220b1e0",