Version: (using KDE 4.3.0) OS: Linux Installed from: Ubuntu Packages To remove a widget from a panel in Plasma one just has to right click on it and select "Remove this ...". Although in many cases it might be user friendly to not have to confirm the removal, it can lead to accidental removals of possibly important widgets. I experienced this especially with the system tray and the window panel. To close an application in the system tray I right click on its symbol and then on the option that has the red "X". If I accidentally didn't click on the symbol but on some place inside the system tray and don't notice this, the system tray disappears. I then have to add and reconfigure it. Adding a confirmation message could prevent this.
*** This bug has been marked as a duplicate of bug 175270 ***