Created attachment 3741 
gdb backtrace

Steps to reproduce:

- add the "Window Buttons"-applet to a panel
- choose "None, allow drag-and-drop" as the sorting order
- open two (or more) different applications, e. g. thunar and the Xfce terminal
- drag the last window button within the task list and drop it on the window button next to the dragged one (for example, if you have three window buttons, drag the third one and drop it on the second)
- all window buttons disappear except for one, xfce4-panel receives segmentation fault, then crashes (or hangs the whole desktop)

However, the behaviour isn't always the same - sometimes there is no crash at all, or the panel just disappears. It's a bit tricky to reproduce ...


Using xfce4-panel 4.8.4, gtk+ 2.24.5, xorg-server 1.10.2