LOOPIF conditional loop begin:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Syntax:
~~~~~~~

  LOOPIF <Expr>

Description:
~~~~~~~~~~~
If the expresion <Expr> is true, the LOOP is performed.

Example:
~~~~~~~~
  REPEAT
    nKey:=InKey(0)
    LOOPIF nKey==K_ENTER
    DO CASE
      CASE nKey==K_UP
        ...
      CASE nKey==K_DOWN
        ...
      OTHERWISE
        ...
    ENDCASE
  UNTIL nKey==K_ESC
  ...

All pressed keys are handled without K_ENTER, the loop is finished after
pressing of th ESC key.

Source file is Object.ch