Selecting one file with inproper extension cancels the whole selection

Say I have a file field that accepts only pdfs.

Now I select 30 pdf files and accidentally also one doc file. When I click 'Open' in the file selection box I get an error message, that the doc file cannot be uploaded. The problem is that I have to do the whole selection thing again for the pdfs too. It would be nice if the correctly selected pdf files would still appear in my file list.