Hello everyone,

Trying to go further in the configuration kde (I'm on Kubuntu 14.04) I went by right clicking on the desktop -> Desktop default configuration -> Mouse actions.

Thinking could go back I changed "Standard menu" to "Application Launcher"
nothing on system configuration and nothing on the internet impossible to replace the standard menu

Thank you for your help

Lanzaroto

I reply to myself

I found the solution from the plasma button in the upper right by default (the one that is also used to lock the graphical components), there is a menu which provides access to desktop configuration .