Hi Toad.
I know you are probably venting and didn't expect an actual Toad developer to read this, but that's who I am. An actual Toad developer. I put a LOT of effort into fixing bugs.
Which Toad version are you on? I fixed a bug like this in Toad version 15.0. Search for "cancel" on this page for details. There are 2 bugs on that page that may be relevant. If your case is different, please give me whatever details you can about how to reproduce it and I'll do what I can to fix it.
In the meantime, you might want to try using the threaded query option. That way your query executions aren't blocked by a popup cancel button. Instead you can just go to a different editor tab and keep working. To turn this on, go to Options -> Oracle -> Transaction. Check "Execute queries in threads".
-John