Fix window list on vertical panels

[slacka]

For those of us with wide screen monitors, it would be great if we could have a panel that works well in the vertical position. We have additional space for a wide vertical panel on the right or left side of our monitor.

Steps to reproduce the problem:

1. Create a vertical panel (mine is on the Left)
2. Add a Window List to it and experiment with the size settings
3. Set the width to 30-75 pixels
4. Open more than 7 windows

Result:
Windows List will rapidly flip between one column and two columns, spiking the CPU and making the panel unusable.

There are several patches for this bug that were never accepted into the main line. Here are some resources:
https://bugzilla.gnome.org/show_bug.cgi?id=86382
http://brainstorm.ubuntu.com/idea/1906/
http://versia.com/2009/09/vertical-panel-in-gnome-15-months-later/
https://bugs.launchpad.net/hundredpapercuts/+bug/389407

[stefano-k]

9ba2a75
mate-desktop-legacy-archive/libmatewnck@6410ce0

[slacka]

@stefano-k
Please reopen this bug for mate 1.8. It was working in 1.6.1, but is broken in the latest mint 17.

[stefano-k]

Because 1.8 uses libwnck, so you need an updated libwnck
The issue is not is mate-panel

[monsta]

@stefano-k: is it known what minimal version of libwnck is needed for this to work?