So, I'm running on kubuntu 15.04 using the 5.3 kde-plasma. I think that plasmoid or something like the draw with mouse desktop effect whould be really helpfull if it doesn't overlap everything. I'm looking after something wich whould allow me to draw over my desktop wallpaper only, being overlaped by everithing else. In another words, drawing with mouse over desktop whille the windows can cover everithing that I drew. Is there something like this?

If it have all shortcuts to change color and erase it whould be amazing for me.

There's a blackboard widget that does this. Unfortunately it doesn't seem possible to set it as the desktop type (like e.g. Folder View), you could maybe file a request for that at http://bugs.kde.org.