Add deselect all checkbox when importing files

[Cristian Antonuccio]

When importing files with hundreds of tracks and you only need one is often time a very slow task to manually deselect all of them. If there was a checkbox in the top filter (I highlighted the spot in red in the screenshot) it would make the selection process way better.

[Damiano Galassi]

You can select them all (From the edit menu or cmd-a) and select deselect in the contextual menu..