If you're playing Diablo II in wine, the default Alt+Click mapping in Cinnamon (which moves the underlying window) is kind of annoying. Since the desktop environment is based on Gnome (I guess), you can use the gconf-editor tool to edit the mappings.
Under Mint 13, the configuration editor isn't installed by default, so you might have to do this:
sudo apt-get install gconf-editor gconf-editorThen navigate to apps/metacity/general and edit the mouse_button_modifier key to something else (I used "Control" which seems to be fine).
Getting "pick up items with Alt held down" to work
Holding down Alt highlights items. If you can't pick up items with Alt held down, you may need to disable the window manager control of the wine window.
To do this, run winecfg, go to Graphics tab, and uncheck the "Allow the window manager to control the windows" option.
Alt+Click for item pick up now works. The downside is that the window won't appear in the taskbar any more, and when you minimise it you get a little icon in the bottom left-hand corner. But it works.
Note: While initially I did this and it seemed to helped, it might also cause keyboard interaction to stop working. I was playing around with the "Window focus mode" in Cinnamon -> Window Settings at the same time, so at the moment I've turned the window manager control back on in winecfg and it's okay.