Thanks for the file! When I tested it, everything seemed to work OK on our end as well. That is, I opened the "Registro" Page and increased the font size for all the text, which then remained visible in the Design Area.
To investigate this further, could you help answer the following questions, below?
What version of Windows or Mac OS X are you running?
Could you record a brief video/screencast of this happening? For recording screencasts, you can use the same tool that the original poster, Neilbahl, used. You can get the free download here: Download Jing
Seeing how you're able to reproduce this error will be a great help.
- Does this error happen in all files? Could you test this in a new file, i.e. via "File > New"?