public void Drop()
	{
		//assume the block can drop unless we find otherwise
		boolean movable = true;

		for( int i = 0; i < 4; i++ )
		{
			int newLevel = currentBlock.yvalues[i] - 1;
			//if there is something below currentBlock then it can't
			//go any further down
			if( currentBlock.yvalues[i] == 0 ||
				colorGrid[newLevel][currentBlock.xvalues[i]].isSet == true
				 )
				movable = false;
		}

		//if it can move then decrement the y values
		if( movable )
		{
			for( int j = 0; j < 4; j++ )
				currentBlock.yvalues[j] -= 1;
			currentBlock.yposition--;
		}
		//otherwise set it into the grid
		else
		{
			for( int k = 0; k < 4; k++ )
			{
				colorGrid[currentBlock.yvalues[k]][currentBlock.xvalues[k]].isSet = true;
				colorGrid[currentBlock.yvalues[k]][currentBlock.xvalues[k]].r
						= currentBlock.red;
				colorGrid[currentBlock.yvalues[k]][currentBlock.xvalues[k]].g
						= currentBlock.green;
				colorGrid[currentBlock.yvalues[k]][currentBlock.xvalues[k]].b
						= currentBlock.blue;
			}
			BlockIsActive = false; //since the block has been added to the
									//grid it is no longer active
		}

	}