You can use a variable that holds the state of the game...
Code:
var game_paused = 0;


So when you press 'pause' you can check this variable and act accordingly...
Code:
function PausePressed()
{
if(game_paused == 0) // game not paused
{
// show pause menu
set(pnl_pause_menu,SHOW);
game_paused = 1;
}
else // game already paused
{
// hide pause menu 
reset(pnl_pause_menu,SHOW);
game_paused = 0;
}
}