Text Boxes are used to write annotations on a chart.
To add the tool to your chart, select the tool from the Drawing tool group, and left-click on the area where you wish to add the tool. Next, type the text that you want displayed. Optuma will then draw the tool using the default settings.
This is a companion discussion topic for the original entry at https://www.optuma.com/kb/optuma/tools/drawing/text-box