Place cursor state on the stack, optionaly change state
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 Syntax

        GT_PUSHCUR([<nNewState>]) -> <nOldState>

 Arguments:

      <nNewState> is a numeric constant which identifies the new cursor
                  state.  Manifest constants from setcurs.ch are
                  recommended.

 Returns:

      <nOldState> is the state of the cursor before any changes are
      applied.

 Description:

      This function pushes the current cursor state onto a stack, and then
      optionaly changes the state.  To restore the cursor is simply a
      matter of 'popping' the stack by calling GT_POPCUR().

      It is important to pop the stack as many times as you push it,
      otherwise you may get the wrong cursor shape back.

 Examples:

      GT_PUSHCUR(SC_NONE)   // push cursor and turn it off
        ..code..            // do something, maybe display a message
        ...
      GT_POPCUR()           // restore cursor

 Header File: SETCURS.CH  GT_LIB.CH

 Source: GTCURS.PRG

 Author:  Philip Ide