Hi OLC - I'm looking forward to your new update. Time for a new patrol, I think.
I noticed you were going to make your depth tool draggable. I do use the draggable protractor tool a lot in your mod & have managed to drag it too close to the edge of the chart and been unable to retrieve it.

An obvious & simple solution is, probably, not to drag the tool too close to the edge of the chart, but if you do want to make your mod idiot proof......