**
Gdk:ERROR:../gdk/quartz/gdkdnd-quartz.c:43:gdkquartzwindowdragbegin: assertion failed: (gdkquartzdragsourcecontext == NULL)
Bail out! Gdk:ERROR:../gdk/quartz/gdkdnd-quartz.c:43:gdkquartzwindowdragbegin: assertion failed: (gdkquartzdragsourcecontext == NULL)
Abort trap: 6

Workaround is to click and then use the keyboard to copy text.