public enum TransformCategory
The categories of matrices relevant for GSK and GTK.
Note that any category includes matrices of all later categories. So if you want to for example check if a matrix is a 2D matrix, `category >= GSK_TRANSFORM_CATEGORY_2D` is the way to do this.
Also keep in mind that rounding errors may cause matrices to not conform to their categories. Otherwise, matrix operations done via mutliplication will not worsen categories. So for the matrix multiplication `C = A * B`, `category(C) = MIN (category(A), category(B))`.