WDL function is used...

Example (scriptname.wdl):
WINDOW WINSTART
{
TITLE "My Simulator";
SIZE 480,320;
MODE IMAGE;
BG_COLOR RGB(240,240,240);
FRAME FTYP1,0,0,480,320;
BUTTON BUTTON_START,SYS_DEFAULT,"Start",400,288,72,24;
BUTTON BUTTON_QUIT,SYS_DEFAULT,"Abort",400,288,72,24;
SET FONT "Arial", RGB(255,255,255);
TEXT "Get ready...", 0,0;
TEXT_STDOUT "Arial",RGB(0,0,0),10,10,460,280;
BG_PATTERN <background.pcx>,OPAQUE;
PATTERN <checker.pcx>,OPAQUE,50,50,100,100;
PICTURE <splash.pcx>,OPAQUE,10,10;
PROGRESS RGB(0,0,255), 10, 0, 300, 400, 20;
COMMAND "-diag";
}

WINDOW WINEND
{
TITLE "Finished";
SIZE 540,320;
MODE STANDARD;
BG_COLOR RGB(0,0,0);
TEXT_STDOUT "Arial",RGB(255,40,40),10,20,520,270;
SET FONT "Arial",RGB(0,255,255);
TEXT "Any key to exit",10,270;
}