Ease effect on collapsing menu

programming flash
1

Hello! Referring to this senocular menu, ho can I add an ease effect for collapsing submenu sections? Here il the code for menuOpen and menuClose:


// MenuOpen: this function opens a menu when its title is clicked
MenuOpen = function(){
	var menu = this;
	menu.masker._height += (1+menu._height-menu.title._height)/anim_frames;
	/* menu.masker._y += menu.masker._height;*/
	if (menu.masker._height >= menu._height){
		menu.masker._height = menu._height;
		delete this.onEnterFrame;
	}
	PositionMenusBelow(menu.i);
}

// MenuClose: this function closes a menu when its title is clicked
MenuClose = function(){
	var menu = this;
	menu.masker._height -= (1+menu._height-menu.title._height)/anim_frames;
	if (menu.masker._height <= menu.title._height){
		menu.masker._height = menu.title._height;
		delete this.onEnterFrame;
	}
	PositionMenusBelow(menu.i);
}

Thank you!
Paolo