Bug 1306298 - Close any pre-existing print progress dialogs when on re-entry to print preview. r=mconley

toolkit/components/printing/content/printUtils.js

@@ -207,6 +207,13 @@ var PrintUtils = {
       // issues in bug 267422.
       let ppBrowser = this._listener.getPrintPreviewBrowser();
       ppBrowser.collapsed = true;
+
+      // If the user transits too quickly within preview and we have a pending
+      // progress dialog, we will close it before opening a new one.
+      if (this._webProgressPP && this._webProgressPP.value) {
+        this._webProgressPP.value.onStateChange(null, null,
+          Components.interfaces.nsIWebProgressListener.STATE_STOP, 0);
+      }
     }
 
     this._webProgressPP = {};