A handy little feature, that would allow you to insert markers into the pattern sequence, to visually indicate different parts of the song. Or in my case, different songs in the multi-part song file.
Here's a suggestion mock-up of how it could look like:

By right-clicking the Sequence editor, you would get an "Insert Marker" command. The marker name would be editable. The markers would be placed "between" patterns. This seems more logical to me, as it visually marks the beginning of a pattern.
By right-clicking the marker tag, you could select "Delete", "Rename", "Delete All Markers" and "Anchor to Sequence (red) / Anchor to Patterns (blue)". The difference between the aforementioned two would be, that a marker anchored to the Sequence would retain its absolute position in the sequenxe, whereas a marker anchored to the patterns would shift and move as patterns are inserted or deleted.
Markers could be moved by dragging.
Floating the mouse cursor above a marker tag would show its Position in the sequence (both in decimal and hex). This would be helpful when entering Bxx commands.