wrap workspaces works incorectly with non-rectangular screen layout

Submitted by ari..@..usi.de

Assigned to Olivier Fourdan @olivier

Link to original bug (#8574)

Description

The total screen layout may be non-rectangular, typical in multi-screen-setups [1]. Then xfwms options "wrap workspaces when dragging a window off the screen" and "Wrap workspaces when the pointer reches the screen edge" do nothing when the pointer hits one screens boarder when it does not coincidences with the bounding rectangle

[1] I currently have a 1680x1050 screen above a 1400x1050 screen, left sides aligned, wrapping when hitting the right side does nothing

Version: 4.8.0