Using a hidden Task manager in a autohidden panel on the left hand of my screen. This pops up inconveniently at any change in the workspace. Adding a new window will pop it up for example. After that it doesn't even hide again until you have ran the mouse by it.
This is fixed in newer versions of Plasma (KWin) but the patch was too invasive and risky to be backported to LTS, sorry. (Basically whenever a geometry change request was posted for the panel (e.g. implicit size of Task Manager changing due to items being added/removed) KWin would unhide the panel as it could have moved out of the visible are and become unreachable. It then didn't re-apply the auto hiding)