Hi,
I was wondering if there's any way to create a drop down icon to click that can open/close groups of cells in Mathematica.
I saw some examples of notebooks and in Wolfram documentation that has arrow at the left corner to expand the cells however I couldn't find the option to create it anywhere.
At the moment I open/close group of cells by double click it at the right corner however, it looks very inconvenient to do so.
Thanks
