When I select a text box, there is no Add to Library edit tool. How can I add a text box, such as one that contains notes I want to use on future plans, to the Library Browser for future use?
Although the Add to Library edit tool isn't available for a single text box when you initially select it, you can block a text box to itself, create a CAD Block, and add that CAD Block to the Library Browser.
To add a single text box of notes to the Library Browser
Using the Select Objects tool, click and drag a marquee around the Text box.
Once a marquee has been drawn around the text, so it is selected, click on the Make CAD Block edit tool to block the text to itself
Once a CAD Block has been created, then you can click the Add to Library edit tool to add the text to the Library in your User Catalog, where you can give it a descriptive name and place it in a folder for use in future plans.
If you place the text in a plan from the Library Browser, and then find you need to modify it in that plan, then simply select the CAD Block and click on the Explode CAD Block edit tool.