I would like to be able (e.g. with a DesignerAction) to refresh the DataSource while the designer is already running.
Ideally, this would include possible changes to the schema. I would also however already benefit merely from a solution where the schema has to remain identical, but the content changes.
This would be really a helpful feature. I implemented my own IDataProvider and hoped I can set ll.Datasource = null and afterwards to a new instance of my DataProvider object.
If this would work, I could provide extreme values for design time and can check needed layout changes faster. Currently I have to save the project, start the project again with minimal values, check, eventually change, save, start over again check with maximum values, again and so on.
I know this could be hard to implement because of possible internal caching mechanisms of LL, but the feature must only work in Designer mode 
I’m also fine if only the content changes, no need to check for schema changes.