hi Oichan, mozilla is looking into this matter in [https://bugzilla.mozilla.org/show_bug.cgi?id=1359624 bug 1359624]. if you are a technically inclined user, could you be willing to help us debug this? it would be of great help if you can install the mozregression tool like described at http://mozilla.github.io/mozregression/install.html this tool will download and execute various firefox builds and asks you if they are affected by the issue or not until you find the exact change or regression range of when this bug was introduced...