I want to allow my users to create a custom table, i.e. not only add/remove rows but also add/remove columns. To make this work, I probably need to build a custom widget that shows column & field objects (correct me if I'm wrong). However, I'd also like to allow Excel import for this custom table, but I wonder whether this is possible with the default Excel importer. Is there a way to import an undefined set of columns or is this not going to work since no mapping has been created design-time?