There are too many messageboxes with questions in case of unused parameters in "Create Element with Command Line Tool" dialog

Scenario:

1. Open the Workflow Designer.
2. Click on the "Create element with command line tool" button on the toolbar.
3. Enter any valid name.
4. Click the "Next" button.
5. Click the "Add input" button.
6. Set any valid name for the added input entry.
7. Click the "Add output" button.
8. Set any valid name for the added output entry.
9. Click the "Next" button.
10. Click the "Add attribute" (or "Add parameter", if UGENE-6420 has been been already done) button.
11. Set any valid name for the added parameter.
12. Click the "Next" button.
13. Replace the execution string with "qwe".
14. Click "Finish" button.
    Current result: three message boxes will be shown one after another. They contain information about names that were unused in the execution string.

One message box should be shown. It should contain information about all inconsistencies in the execution string. Add a scrollbar, if there are too many inconsistencies.