Debug icon appeared after upgrade from Oracle 9i to 10g
After an upgrade from Oracle 9i to 10g database the debug icons appeared next to procedures, packages, functions in schema browser
Toggling Compile with Debug Information:
To use the debugger fully with the PL/SQL or Java packages, you need to compile your object with debug information. If you have not compiled with debug information, in databases in versions before 10g you can step into a unit, step over and so on, but you cannot see watches unless the object is compiled with debug. In a 10g database you cannot step into code or step over unless the object was compiled with debug. You can only execute.
To compile with debug information:
From the Session menu, select Toggle Compiling with Debug Information. Note: By default this option is selected when you open the Editor. If you want it to default to unselected, you can change it in Toad Options|Editor|Debugging|Default to "Compile with Debug."