Currently, hiding the 'more' button in the of the DataGrid filter Options panel is not possible. This is a feature request to add such an option to the DataGrid column styling options (potentially as a property of the HeaderStyle).
Currently, all groups are expanded by default. We should expose methods to collapse/expand certain groups. Furthermore, CollapseAll, ExpandAll groups should be considered as well.
The DataGrid documentation is missing a Styling article. It should cover how to use the following: - DataGridBorderStyle (and how it's used for the RowBackground styles and SelectedStyle - DataGridTextCellStyle (especially how as the CellContentStyle it lets you set the SelectedTextColor) - DataGridLoadOnDemandStyle - DataGridColumnHeaderStyle - DataGridGroupHeaderStyle - DataGridHeaderStyle I think the Styling section might need it's own node with a few articles as the information would be too large for one article