
Is your custom font based on an actual font file (.ttf or what have you), or is it a pixmap (imageset based) font? If the former, does your custom font have auto-sizing enabled? Finally, what is the order of operations in the resize code now?
With regards to 'texture backing', this is a new facility in 0.7.0 to render GUI content to a texture prior to drawing it on the screen. This serves multiple purposes, such as increasing performance in most cases, and also facilitates window level rotations and other effects. If you've not specifically enabled this, and since you're using a custom skin, you're correct that you're almost certainly not using this (so do not have to worry about the bug that exists there).
CE.