Inkscape and the Alt key in Unity (Ubuntu 14.04.1 LTS)

System: Ubuntu 14.04.1 LTS
Problem: Unity "steals" the Alt-key so that it doesn't function as it should in Inkscape.

Solution:

• install dconf-tools
• launch it
• go to org -> gnome -> desktop -> wm -> preferences
• set "mouse-button-modifier" to "<Super>" (without the quotation marks).
  DO NOT SET IT TO "none" or leave the field empty, or you won't be able to left-click normally anymore anywhere in Unity (I know because I made the mistake, had to log out and log in to Xfce to correct it, Unity was totally messed up).

(With thanks to this post but take caution not to set the value to "none"!)

How to free the Alt-key in Xfce for inkscape, Blender, etc.

As explained on the Inkscape FAQ:

• To enable in XFCE 4.4 or greater, in the Settings Manager > Window Manager Tweaks > Accessibility Tab, change "Key used to grab and move windows" to "none" or something else. Several other selections (such as "Meta") may still use the "Alt" key, however, so test it first.