Question: Help with command line debugger

For the following Maple 2015 procedure and funtion call

 f := proc(x,y) local a; global b;
    if x < y then
        a := x; b := y + a;
    else
        a := y; b := x + a;
    end if;
    a + b + x + y
end proc:
stopat(f);
                              [f]
f(2, 3);
 

Maple help topic "The Maple Debugger" shows the following example:

 f:
    1*   if x < y then
           ...
         else
           ...
         end if;
 
 DBG> stopwhen b
 [b]
 f:
    1*   if x < y then
           ...
         else
           ...
         end if;
 
 DBG> cont
 b := 5
 f:
    6    a+b+x+y
 
 DBG> showstat
 f := proc(x, y)
 local a;
 global b;
    1*   if x < y then
    2      a := x;
    3      b := y+a
         else
    4      a := y;
    5      b := x+a
         end if;
    6 !  a+b+x+y
 end
 
 DBG> quit
 Warning, computation interrupted

However, when I run the procedure in Maple Notation (1D) the Interactive Maple Debugger pops up with syntax quite different from the example.  How can I turn the Interactive Debugger off and use commands such as DBG> stopwhen b in the command-line version?

Thanks!  Les