If you close out the preference dialog (i.e., not Cancel it) I was able to debugged that multiple GTK3 delete-events occurred. This causes EtheApe to crash ( A NULL temp preference structure is copied into the primary preference structure). This patch is a work around and detects if a delete-event has already occurred.

I could not figure out why multiple (i.e. 2) delete-events occurs when the X Button for closing out the preference dialog window is happening. I am using Fedora, with the mate desktop.