In Kde-Neon LTS 5.12 the upper left corner is too busy. First the active corner is active with "show all windows", then the Plasma Toolbox-Icon is there too and the Installer icon is right next to it. It is especially confusing when I click the toolbox-icon and hit the active corner at the same time. For my taste, the active corner should be disabled and the Installer icon aligned on the right side of the Desktop.
*** This bug has been marked as a duplicate of bug 390038 ***