FOUND A SOLUTION!
I posted to the thread you mention but I paste it here too:http://forums.linuxmint.com/viewtopic.php?f=208&t=104756&p=686463#p686463
I wanted to test if this fix you mention actually worked for me too (Cinnamon 1.4) so I switched the panel to edit mode, moved the window-list furthest left, turned edit mode off, and it did work. I opened 10+ windows and only the actual windows were getting squeezed. The applet was not expanding to the right. I wouldnt want it like that so I just confirmed the solution was valid for me too. So I moved it the same way back to the original place, turned edit mode off and surprise surprise!
The applet does not resize any more! Strange huh? I also logged off and also restarted to be 100% sure it stays like that and it does! Did this work for anyone else?