Bug 353560 - Unknown Content dialog not dismissed when filepicker opens. r=gavin.

toolkit/mozapps/downloads/src/nsHelperAppDlg.js.in

@@ -885,7 +885,12 @@ nsUnknownContentTypeDialog.prototype = {
 
           this.mLauncher.saveToDisk(targetFile, false);
 #endif
-          this.mLauncher.saveToDisk(null, false);
+          // Since saveToDisk may open a file picker and therefore block this routine,
+          // we should only call it once the dialog is closed.
+          var _delayedSaveToDisk = function(aSelf) {
+            aSelf.mLauncher.saveToDisk(null, false);
+          }
+          this.mDialog.opener.setTimeout(_delayedSaveToDisk, 0, this);
         }
         else
           this.mLauncher.launchWithApplication(null, false);