Framing lumber trading in the US experienced mix trends during last week. While the rally in Canadian S-P-F settled back into a calmer and quieter pace, sales of Coast dry and Southern Pine picked up.   Green Douglas Fir, meanwhile, was vulnerable in certain items at some mills, leaving traders of that species off balance. Sales of 2x4 studs were solid, and key prices posted gains through the week. All told, gainers outnumbered losers and the Random Lengths Framing Lumber Composite posted a $2 increase.     Week Apr 13  ...