Feature Request: Option to disable alt+middle_click functionality

Submitted by Jackson

Assigned to Olivier Fourdan @olivier

Link to original bug (#15986)

Description

(Note: Alt here refers to whatever 'Key used to grab and move windows' is set to)

alt+middle_click as of right now sends the current window to the back of the stack, however I would like to use this as a shortcut in my text editor so I would appreciate the option to disable this functionality. I believe the code pertaining to this mouse event (at time of writing) is at https://git.xfce.org/xfce/xfwm4/tree/src/events.c#n933

Version: 4.14.0