Fix for Ignored Mouse Clicks at Left Edge of Screen in KDE

This has been driving me nuts for years. The problem is that when I move the mouse to the far left edge of the screen, my mouse clicks are ignored. I can't right click to bring up the context menu, I can't use the scroll wheel to switch virtual desktops. The latter is my particular pet peeve because I always leave a gap at the left edge of the screen, and when I want to change desktop I just move the mouse over there and scroll.

It turns out the culprit is touch screen support in KDE. There is a screen edge gesture that is enabled by default, and when it is enabled it creates an invisible one pixel wide window at the edge of the screen. That window steals your mouse events from the desktop.

To fix, open the KDE System Settings tool, go into Workspace->Desktop Behavior->Touch Screen. Click the button on the left edge of the screen image and select No Action. Restart KDE and the problem will be gone.

The worst part about this is I'm pretty sure I fixed it once in the past, but I forgot how and couldn't find the bug that explained what was going on. This time I'm writing down the solution for future reference. :-)