VGA28()
 Switches to 28-line VGA mode
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 Syntax

     VGA28() --> lStatus

 Returns

     VGA28() returns .T. when the screen adapter that you use (VGA only)
     successfully switches to this mode.

 Description

     In order to generate a pixel height of 14, like that of EGA (for
     instance, to use the accompanying font editor on a VGA adapter), this
     mode must be implemented.

 Note

     Important!  This function cannot be used when windows are open.

 Example

     Switch to 28-line mode:

     IF ISVGA()
        VGA28()
     ENDIF

     @ 27, 00 SAY CENTER("CA-Clipper")       // Last screen line

     WAIT

     CGA80()                                 // Return to 25 line
                                             // mode