I am kind of still struggling to get the following under one hat:

1) Use a number of Plasma applets
2) Don't clutter desktop with applets that are seldom but regularly used (see also https://bugs.kde.org/show_bug.cgi?id=382872))
3) Being able to group several applets that have a common purpose (e.g. there are different system monitoring applets with each are good at a specific task but neither combines all features)
4) Being still able to quickly access the applets (especially those that are only occasionally used)

Recently, I try to use an auto-hide panel for different monitoring applets but the downside is that there are only 4 screen edges and on either side it bothers when the mouse is accidentally touching it (which causes the panel to appear) while trying to click buttons or using scrollbars on the current application window.

Today, I had the following idea:

What about being able to create a panel that can be opened or closed by clicking an icon in the main panel or the system tray? This way, the panel is always out of the way when not needed, can be accessed quickly and is still fully configurable with applets.