Project Default Properties error

Bug:
I converted a project from ScriptCase 7 to ScriptCase 8, it succeeded, and I loaded that project.

I select Project -> Default Properties and the default properties are displayed.

I changed the default Grid lines from 10 to 20, click Update, and get this error:
[INDENT]Themes The string can only contain letters, numbers and underscore.[/INDENT]

I don’t see where a theme is defined within Default Properties.

Workaround:
Don’t use Default Properties.