Mark a Screenshot on Linux

More that than often to explain things quickly, I like to take a screenshot of the (web) application I am talking about, and then circle the corresponding area so that everything is clear. Possibly with a rounded rectangle, as I find it the cutest variant.

This is how I do it on Linux:
Install necessary tools:

apt install gimp scrot                                                                   

Take the screenshot:

# Interactively select a window or rectangle with the mouse                              
scrot --selection screenshot.png                                                                    

Open the screenshot and annotate it with gimp:

gimp screenshot.png                                                                      

Then in gimp:

• Tools -> Selection Tools -> Rectangle Select, and mark the area
• Select -> Rounded Rectangle, and keep the default
• Change the color to a nice blue shade in the toolbox
• Edit -> Stroke selection

Maybe gimp is a bit overkill for that. But instead of learning a limited tool, I prefer to learn an advanced one like gimp step by step.