As we decided to make the OSD available only for certain things, the API is intentionally limited to very particular set of things. The list is not complete yet I believe, but I'd like to get comments on the general design and state.

Also as it's not a public service, I left it under org.kde.plasma_shell on D-Bus. Makes sense? Does not? Should it be standalone at eg. org.kde.osd?

Note: This still needs patches in kwin.

Can be invoked using qdbus from command line. Works rather well.