I have to answer my own post to add a next image that will explain better the issue. Excuse me.
Marc VAN ASSCHE:
Thank you for your post.
What version of FileMaker Pro 12 are you using? When using Mac OS X 10.9.2 (I'll assume 10.9.3 is a misprint), make sure you have updated to FileMaker Pro 12.l0v5, as it is the only version tested to work with Mavericks.
Does this issue only occur with this one file? If you create a new layout, does the issue still occur? If you try this with a new file, does the issue occur?
Any other information you can provide may be helpful in determining possible causes.