Weird auto-resize max width when touching top of desktop with a window
*new feature introduced in xfce 4.10 : tiling windows on border" needs to be OFF by default. Settings Manager (xfce4-settings-manager) > Window Manager Tweaks > Accessibility > Automatically tile windows when moving toward the screen edge
As it caused a lot of annoyance for many.
As per forum discussion here: https://forum.xfce.org/viewtopic.php?pid=72303#p72303