Version:           SVN r759781 (using KDE Devel)
Installed from:    Compiled sources
OS:                Linux

When I deselect the option "Show Desktop Icons" in the "Configure Desktop" dialog, the icons disappear as expected.  After restarting plasma (either logout and login, or kquitapp plasma; plasma) they are back, and the option is selected again.

After changing the setting, then running kquitapp plasma, neither plasmarc nor plasma-appletrc have a "DesktopIcons" group or a "showIcons" key.

I put this:

kDebug() << "Writing showIcons=" << (m_showIcons->checkState() == Qt::Checked ? true : false)
             << "to config group" << iconConfig.name()
             << "in config file" << iconConfig.config()->name();

At the end of BackgroundDialog::saveConfig(), and I get this line:

plasma(11484) BackgroundDialog::saveConfig: Writing showIcons= false to config group "DesktopIcons" in config file "plasmarc"

Placing iconConfig().config()->sync() at the end of BackgroundDialog::saveConfig() fixes the problem (the setting is saved and plasmarc gets a [AppletGlobals][plasma_containment_desktop][DesktopIcons] group with the correct keys), but this shouldn't be necessary, surely?