window.onload = function()
{
	mainBlock = document.getElementById('main_block');
	headerBlock = document.getElementById('header_block');
	topBlock = document.getElementById('top_block');
	middleBlock = document.getElementById('middle_block');
	leftBlock = document.getElementById('left_block');
	centralBlock = document.getElementById('right_block');
	rightBlock = document.getElementById('central_block');
	
	if (mainBlock && headerBlock && topBlock && middleBlock && leftBlock && centralBlock && rightBlock)
	{
		desiredHeight = parseInt(mainBlock.offsetHeight) - parseInt(headerBlock.offsetHeight) - parseInt(topBlock.offsetHeight) - 7;
		if (desiredHeight > parseInt(middleBlock.offsetHeight))
		{
			middleBlock.style.height = desiredHeight+'px';
			leftBlock.style.height = desiredHeight+'px';
			centralBlock.style.height = desiredHeight+'px';
			rightBlock.style.height = desiredHeight+'px';
		}
		else
		{
			middleBlock.style.height = middleBlock.offsetHeight+'px';
			leftBlock.style.height = middleBlock.offsetHeight+'px';
			centralBlock.style.height = middleBlock.offsetHeight+'px';
			rightBlock.style.height = middleBlock.offsetHeight+'px';
		}
		middleBlock.style.visibility = 'visible';
	}
}