As of this writing Plasma ships with a feature (System settings > Workspace > Screen edge) allowing users to have hovering the mouse cursor near a screen edge as a trigger for various actions. The problem is that these actions -- however useful -- are quite limited. For example there is no support for actions like open Simple Menu plasmoid when hovering over top horizontal edge. This raises two questions:
1. Is there any non-built-in way of doing precisely that?
2. Where can I submit a Feature Request for supporting customizable screen edge actions out-of-the-box?

You can always suggest new features in the brainstorm section of this forum, or file a wish directly in https://bugs.kde.org