After testing my backported packages on a clean install. I've found a problem with the following packages:
* xfce4-mixer
* xfce4-battery-plugin
* xfce4-clipman-plugin
* xfce4-cpugraph-plugin
* xfce4-datetime-plugin
* xfce4-genmon-plugin
* xfce4-mailwatch-plugin
* xfce4-mount-plugin
* xfce4-timer-plugin
These packages are currently identical in both jessie and stretch/sid, but they need a little bump in unstable to be rebuilt against newer xfce4-panel libs.
While this is not done yet, how could I make this bump with my own backported packages? Which package release suffix should I use (since default "~bpo+1" won't work)?