At every (re-)boot the icons on the desktop get re-arranged. This has just started with last upgrade of my LinuxMint a few days ago... I've seen similar bug reports from 2011, which incriminate a change in the screen resolution (or detection of a new screen, at startup?), but they are supposed to be resolved...
The window manager is not responsible for the icons on the desktop, xfdesktop is.
Sorry for the wrong classification... Apparently, logging-out then logging-in again works. It's only when rebooting that the problem occurrs. With further testing I discovered that if I arrange some icons as if I were using a 1280x768 (1280x800?) screen resolution, and the others as if I were using my "actual" resolution 1440x900 (1440x960?) then only the icons that are "outside" the initial screen resolution get re-arranged. So it's clearly a problem in screen resolution not been set directly to my wished one, but being set to a lower one then changed automatically.
Today, at boot, I noticed that the screen is blinking just after log-in, so it is clear that a screen resolution change occurs when XFCE loads... Trying to move from LinuxMint 17 to 17.1 to seen if anything changes...
Dup of: https://bugzilla.xfce.org/show_bug.cgi?id=11266 Regards.
Indeed, this is the same issue as 11266, let's try to get it corrected there. *** This bug has been marked as a duplicate of bug 11266 ***