As mentioned at https://bugs.kde.org/show_bug.cgi?id=391575 the ShellCorona::activateLauncherMenu() is called through DBus from kwin for two cases. 1. When the user presses the Meta button 2. when the user has chosen a screen edge to trigger this (1) has been addressed because kwin provides a way to set this through kwinrc (2) is hardcoded for plasma DBus interface so Martin proposes that plasmashell should forward the event to Latte if no application launcher menu is found at plasmashell what do you think?
no need... I will create a kwin script for this...