I'm experiencing this same issue. I tried your debugging command above, and when I ran it I was not able to reproduce the crash. After I quit the command and launched plank through the UI in my launcher for XFCE, I could reproduce the issue.
Steps to reproduce:
1. Click UI in launcher for plank.
2. Click on one icon in plank.
3. Drag the icon to another location on plank.
After I did these steps I could reproduce the issue 100% of the time. Is there any other way to attach a debugger?
I'm experiencing this same issue. I tried your debugging command above, and when I ran it I was not able to reproduce the crash. After I quit the command and launched plank through the UI in my launcher for XFCE, I could reproduce the issue.
Steps to reproduce:
1. Click UI in launcher for plank.
2. Click on one icon in plank.
3. Drag the icon to another location on plank.
After I did these steps I could reproduce the issue 100% of the time. Is there any other way to attach a debugger?