The Printer plasmoid in panel is not keyboard navigateable
Reproduce:
Click on printer icon in panel
arrow up/ down or press tab
result:
the list entries (printers) are never focused
only the embedded "play" / "pause" button is not focusable
What should happen:
the list entries (devices) should be focuseable by arrow up / down
pressing tab should focus the "play" / "pause" button for the selected list entry
pressing up /down should move in the list up or down