I did some testing


plasmashell has settled down nicely after ;


 Install dbus-c++-0.9.0-8.fc22.armv7hl                                @updates
    Install dbus-c++-devel-0.9.0-8.fc22.armv7hl                          @updates
    Install dbus-c++-ecore-0.9.0-8.fc22.armv7hl                          @updates
    Install dbus-c++-glib-0.9.0-8.fc22.armv7hl                           @updates
    Install dbus-devel-1:1.8.18-1.fc22.armv7hl                           @updates
    Install dbus-doc-1:1.8.18-1.fc22.noarch                              @updates
    Install dbus-glib-devel-0.104-1.fc22.armv7hl                         @fedora
    Install dbus-java-2.7-17.fc22.armv7hl                                @fedora
    Install dbus-java-javadoc-2.7-17.fc22.armv7hl                        @fedora
    Install dbus-python-devel-1.2.0-7.fc22.armv7hl                       @fedora
    Install dbus-qt3-0.9-13.fc22.armv7hl                                 @fedora
    Install dbus-qt3-devel-0.9-13.fc22.armv7hl                           @fedora
    Install dbus-sharp-1:0.7.0-12.fc22.armv7hl                           @fedora
    Install dbus-sharp-devel-1:0.7.0-12.fc22.armv7hl                     @fedora
    Install dbus-sharp-glib-0.5.0-10.fc22.armv7hl                        @fedora
    Install dbus-sharp-glib-devel-0.5.0-10.fc22.armv7hl                  @fedora
    Install dbusmenu-qt-devel-0.9.2-8.fc22.armv7hl                       @fedora
    Install dbusmenu-qt5-devel-0.9.3-0.3.20140604bzr.fc22.armv7hl        @fedora

with improved reliability, and I have not had an issue since,  still using;

[root@raspi2 yum.repos.d]# uname -a
Linux raspi2 4.0.4-503.20150528git28f888d.fc22.armv7hl.bcm2709 #1 SMP PREEMPT Fri May 29 00:48:23 BST 2015 armv7l armv7l armv7l GNU/Linux

> With FC22 here it seems not necessary.I will try kernel 4 with it.


For stability, you might want to stick with 3.18 branch for the moment.
Don't know whether it was specific to my 4.0.4 build or generically
applicable to the rpi-4.0.y tree, and I haven't had time to investigate
further, but I was experiencing some random lock-ups with rpi-4.0.y
tree, hence the F22 raspberrypi-kernel rpms I made remain in "unstable"