Glad you posted this - users for sure have asked for this over time.

Putting this below for people who may not have noticed also the select range function (goes so well with loop function):

To select a range to loop in the MIDI playback display up top,

click or mouse-wheel scroll the play marker to where you want the section to begin (*also click there and hold brings up a magnified MIDI display to help zoom in to correct points),

then right-click the MIDI player pane, select "start selection at current position",

then mouse-wheel scroll or click to place the playback marker where you wish the selection to end,

and right-click select "end selection at current position"..

then pressing the new 'loop' button, and 'play' will make only the selected range play over and over - and play along/invent and compose or practice

It's taken a while, but, at last. Thank you for adding Loop Function on play bar!
It's brilliant for auditioning sounds and comparing like-for-like passages while editing or A/B ing.

Nice!!! I hadn't noticed this yet, until reading your post.

That's a great addition indeed.