Alternative selection mode

The alternative selection mode partially emulates selection behaviour from early versions of foobar2000.

In this mode, the behaviour when Shift while pressing Up, Down, PgUp, PgDn, Home or End is modified. If the focused item was selected, this action will move the focus while expanding the selection (without deselecting any tracks).

If the focused item was not selected, the focus will move and any items between the old and new focused item will be deselected.

This modified behaviour can be combined with Ctrl+Space to build non-contiguous selections using the keyboard (albeit in a clunky manner).