Export To Disk - Allow all export presets to be unticked

This is an extremely minor request; but one which I find quite irritating. This is on Windows, I assume Mac is the same.

When in the “Export to Disk” window, I quite often need to change the export “Preset”. To do this (depending where on the list the item is); it’s often faster to untick the current preset and tick the desired preset. However this can’t currently be done in PL5.

PL5 requires you to have at least one export “Preset” selected at all times.

I suggest a small change so that all export “Presets” can be unticked; but (obviously) the export button will not be clickable until at least one “Preset” is selected.