function change_submit_button(formname) {
		document.getElementById('upload_submit').innerHTML = '<span class="text_10px text_bold col_rot">Bitte warten...</span>';
		showHideLoadingOverlay();
		document.forms[formname].submit();
	}
	
	function showHideLoadingOverlay() {
		if(Element.visible('loading_overlay')) {
			new Effect.Fade('loading_overlay', { duration: 0.2});
			showSelectBoxes();
		}else {
			hideSelectBoxes();
			// stretch overlay to fill page and fade in
			var arrayPageSize = getPageSize();
			Element.setHeight('loading_overlay', arrayPageSize[1]);
			var img_margin = (arrayPageSize[3]/2)-20;
			Element.setStyle('loading_image',{margin: img_margin+'px auto 0px'});
			new Effect.Appear('loading_overlay', { duration: 0.2, from: 0.0, to: 0.8 });
		}
	}