The TabsPerRow property is only used when the TabStyle resolves to TabsPerRow. When that style is used, this property determines the number of fully visible tabs that will equally share the available tab area. For example, if there is 100 pixels of available area and TabsPerRow is set to 4, each tab will have a logical width of 25 pixels.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2