Clone tool not working on 2.10

[Ofnuts]

(07-21-2019, 01:44 AM)judybosco Wrote: the clone tool has a O with a slash through it

https://en.wikipedia.org/wiki/No_symbol

In Gimp it means that the tool is missing something:

• the cursor is outside the selection
  
• the cursor is outside the active layer boundary
  
• for the clone/heal tools, that you have not set the source yet