insertBefore

pub fn insertBefore(self: *Reorderable) bool {
        if (!self.installed) {
            dvui.log.err("Reorderable.insertBefore() must be called after install()", .{});
            std.debug.assert(false);
        }

        if (self.reorder.drag_ending and self.target_rs != null) {
            return true;
        }

        return false;
    }