The theme used to render the ribbon.
OptionValue can be set to one of the following valid options:
|Office2013||The theme utilized in Office 2013|
|Office2010Blue||The blue theme utilized in Office 2010|
|Office2010Black||The black theme utilized in Office 2010|
|Office2010Silver||The silver theme utilized in Office 2010|
|Office2007Blue||The blue theme utilized in Office 2007|
|Office2007Black||The black theme utilized in Office 2007|
|Office2007Silver||The silver theme utilized in Office 2007|
|Office2007Aqua||The theme utilized in the beta releases of Office 2007|
|Windows7||A theme based on the look of Windows 7|
|System||A theme based on the current system theme settings.|
|Windows10||A theme based on the white Windows 10 theme.|
The Theme property sets the look of the ribbon, and it can mimic every version of MS Office that has utilized the ribbon bar, namely 2007 and later. Simply set one of the aforementioned options and you're done. You can pass any abbreviation so long as it can be reasonably recognized as unique. If the property does recognize the given option, it defaults to "System". For example, "07" will be recognized as "Office2007Blue", but "Office" or "Black" will not because they are too ambiguous in and of themselves.