Created attachment 4322 Fix of the settings-dialog. The default value of the 'show thumbnails' checkbox does not correspond to the default behaviour. The xfconf-property is 'FALSE' if it is missing, so the gui-option is not checked. But the default behaviour is to show thumbnails. This patch forces the default value of the 'Show thumbnails' checkbox to the correct value.
Please apply.
Pushed to master: http://git.xfce.org/xfce/xfdesktop/commit/?id=70d18b52fa09c3ae454d1dab8881d5fad16d324c