In PBI Desktop, I would like to be able to right click on a measure in the Field list and have an annotation field where I can write some notes to myself about why I created the measure the way I did...
This would be also helpful for columns as well. This feature already exists in Tableau and is incredibly helpful in that it not only gives users the ability to make sense of the intention behind a particular measure or column but also appears as a pop-up when users hover on the column. Simple, but effective.
