[Lizard]

Since there's no way to set the completion of a milestone to 100% anyway (maybe there should be, I've filed a bug), I thought up a mildly hackish way to get your 'Completed Milestones' styling.

1. Open Project: Styles inspector
2. Click the '+' button to add a new named style
3. Change its name to "Completed Milestones"
4. Set the Task Bar color for this new style to the same color as your "Completed Tasks" (or another color if you prefer)
5. When a milestone is complete, drag the "Completed Tasks" style onto the milestone in the outline view.

[gillesp]

Completed milestone is something I would really like to have.

[sunshine]

This would be especially good for a milestone only view (hope this gets implemented) and milestone reports. The majority of progress reporting on large projects and programmes is at milestone level.