Filtering a selection in a data library does not inform user they are retained

[hexylena]

I tried to import some datasets from a large library and could not figure out until today why I was getting duplicates imported because the UI didn't communicate that state.

Steps to reproduce

• Go to a library folder with multiple datasets
• Search for a term
• Import the file
• Search for a new term
  • 🐛 There is no indication that I now have 2 datasets selected, and both will be imported, resulting in a duplication of the first dataset.
• Import the file

if the selection had been cleared (as it visually appeared due to lack of notification there were more datasets selected) that would've been fine but I suspect less user friendly.

🐛 So this just needs a little box of "You have N datasets selected, some are hidden by your current filter" (since I guess it's a 'filter' not a 'search' where I'd expect selections to be cleared across.)

💡 This could be additionally be helped by the "Add to history" button or modal popup informing the user of how many datasets they'll be adding. "Import 52 datasets to your history".

Galaxy

usegalaxy.eu, 24.1.2dev0