bbox-annotator | A bounding box annotation widget written in CoffeeScript | Data Labeling library

I'd like to elaborate on the accepted answer to this question.

I'm looking at improving the minimal shiny app below (extracted from the accepted answer) with the following features:

• 1) draw the rectangle + a text label. The label comes from R (input$foo), e.g., from a dropdown. To avoid the edge cases where the labels fall outside the images, labels should be placed inside their rectangles.
• 2) use a different color for the rectangles and their labels depending on the label
• 3) ability for the user to delete a rectangle by double-clicking inside it. In the case of multiple matches (overlap, nested), the rectangle with the smallest area should be deleted.

Brownie points for 1): the dropdown could appear next to the cursor like is done here (code here). If possible, the dropdown list should be passed from server.R and not be fixed/hardcoded. The reason is that depending on some user input, a different dropdown could be shown. E.g., we might have one dropdown for fruits c('banana','pineapple','grapefruit'), one dropdown for animals c('raccoon','dog','cat'), etc.