There was an identical report in Report an Issue recently. That poster resolved the issue by opening the Windows Display Control Panel and selecting the 100% setting. Unfortunately, there are ongoing issues with these settings in windows 7 and FileMaker 13 that can only be avoided at the current time by using the 100% setting--which is often tool small for use with other applications. (For FileMaker, you can often zoom the windows and or select the "enlarge contents to improve readability" preference in order to produce readable layouts.)
Thank you. Guess we'll do that until it gets fixed.