I just tried for the first time to import a 450K line assay library, and while the new ImportTransitionListColumnSelectDlg popped right up and showed me useful information, when I clicked OK (or it could have been Check for Errors) Skyline hung for long enough for me to tire of waiting and click the Pause button in the debugger to see the that I was stuck in the CheckForErrors() function. Hopefully this actually does all of the necessary processing during that check, but it still needs to show a LongWaitDlg with progress the way the old code did before we had to show the column selection form.

Well, actually, it takes 8-10 seconds for the form to show up. So, we need a LongWaitDlg on that side of the operation as well.

And, unfortunately, check for errors is now separated from importing the assay library. So, you see all the errors and then you get a LongWaitDlg saying everything is being imported. At least you don't get the errors again, but in the old model the errors appeared at the end of the import progress.

It would be good to time how long it takes to process the import now versus the time it took for 20.2 (subtracting the time in the new form).

Fixed 3/29/2021 in commit dcea4e65 "Add a progress message for preprocessing step of import of large Assay Libraries and Transition Lists (#1488)"