message: SerialManager_UI: add prefix_placeholder to hold the generic x
diff: @@ -31,7 +31,7 @@ class SerialManager_UI {
  // predefined helper functions, which you can override
  virtual char getIDchar() { return ID_char; }
  - virtual String getPrefix(void) { return String(quadchar_start_char) + String(ID_char) + String("x"); } //your class can use any and every String-able character in place of "x"...so, you class can have *a lot* of commands
  + virtual String getPrefix(void) { return String(quadchar_start_char) + String(ID_char) + prefix_placeholder_char; } //your class can use any and every String-able character in place of "x"...so, you class can have *a lot* of commands
  // here is a method to create the very-common card (button group) to create display a parameter value
  // and to adjust its value with a plus and minus button. Very common!
  @@ -69,6 +69,7 @@ class SerialManager_UI {
  virtual void setButtonState(String btnId, bool newState, bool sendNow = true);
  virtual void setButtonText(String btnId, String text);
  virtual void sendTxBuffer(void);
  + char prefix_placeholder_char = 'x';
  private:
  static char next_ID_char;
  };
  