Feature: window fences

[Björn Fischer]

Hi folks, hi Samuel,

> It is indeed already more in the direction of what i would like to use
> 1. i only need one grid (tried that and it works)
> 2. i do need multimonitor working (you have that in the todo)
> 3. i would like to be able to span multiple 'cells' of the grid

Number 3. is somewhat tricky to integrate into the xfwm native window
dragging workflow. I tried different approaches and failed to come up
with something that is equally intuitive and backwards compatible.

But if it is ok to start the move-resize by hotkey or mouse button
instead of xfwm native dragging, then you may want to have a look at this:

   https://github.com/bjorn-fischer/gridlock


Cheers
Björn