initWithDisplayFn

pub fn initWithDisplayFn(
            // Display the struct using this function, instead of the default struct_ui function.
            customDisplayFn: *const fn (field_name: []const u8, field_value_ptr: *anyopaque, read_only: bool, *dvui.Alignment) void,
            comptime default_value: ?StructT,
        ) Self {
            return .{
                .field_options = .init(.{}),
                .customDisplayFn = customDisplayFn,
                .default_value = default_value,
            };
        }