pbm with pictures dimensions in forums

There is a problem in branch 1.9.x when uploading pictures in advanced settings of forum : dimensions are badly scaled.
see pictures before and after
![forums_and_images_before](https://f.cloud.github.com/assets/4736139/2528004/2da1919a-b50b-11e3-8745-8594badb1922.png)
![forums_and_images_after](https://f.cloud.github.com/assets/4736139/2528003/2d9ff790-b50b-11e3-98c3-0dea65da5a24.png)