What version of FileMaker are you currently using? I'm interested to know if it still occurs in FileMaker 12.0v2.
And what version of what Operating system are you using? My bugs list Database has this listed as "mac only".
For More Information see: Edit Layout/Report in Pro 11 Screen turns to gray when using either of the scroll bars.
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
And FileMaker Inc. does not announce what features/bug fixes will be included in the next update/new version until it is released.
FMP and Advanced 11.0 v4. I own 12 but not ready to migrate to it yet. Mac OS 10.7.4. I've seen this problem I believe since 10.5.x.
So this problem might be fixed--in the FMP 12 release of the product.