I ran across a strange problem while trying to concat long strings:
[code]
void setup()
{
     Serial.begin(115200);
     String first;
     String second;
     String third;
     first = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
     Serial.print("first:");
     Serial.println(first);

     second = "-bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb";
     Serial.print("second:");
     Serial.println(second);

     Serial.println();
     third = first + second;
     Serial.print("third:");
     Serial.println(third);
}
[/code]
The "-" in second produces a cr/lf in the output stream.  Without the "-" things work as expected.
The Arduino user interface works as expected with or without the "-".