Sets up a source for the icon shown on the left of the collapsed group rows.
The Xamarin.Forms.ImageSource object, that specifies the image source.
GridControl provides you with two predefined themes - Light and Dark. The Default theme depends on the mobile platform. For iOS applications, the Default theme is Light, for Android - is Dark. To apply another theme to a grid, use the ThemeManager.ThemeName property. Then, you can customize the applied theme (if needed). For more information, see the How to: Customize Themes document.
To apply customization to a grid, call the ThemeManager.RefreshTheme method.
The CreateArrowRightImageSource method is abstract. So, to change the image source shown in your grid, override the method in the IGroupCustomizer descendants.