g_free() called instead of gdk_device_free_history()
See:
https://gitlab.gnome.org/GNOME/gimp/blob/gimp-2-10/modules/color-selector-water.c#L486
According to the docs the GdkTimeCoord** returned by gdk_device_get_history() should be freed by gdk_device_free_history() instead of g_free()
dragging the mouse pointer over the watercolor selector causes libasan.so.5 to produce this output:
Direct leak of 3400 byte(s) in 85 object(s) allocated from:
#0 0x7fe92af73c48 in malloc (/lib64/libasan.so.5+0xeec48)
#1 0x7fe9261ec200 in g_malloc /home/massimo/devel/obj/glib/glib/gmem.c:99
#2 0x7fe92a391af4 in _gdk_device_get_history /home/massimo/devel/obj/gtk-2-24/gdk/x11/gdkinput-x11.c:863
#3 0x7fe92a37ce3d in IA__gdk_device_get_history /home/massimo/devel/obj/gtk-2-24/gdk/x11/gdkinput.c:488
#4 0x7fe8efb8a74c in motion_notify_event /home/massimo/devel/obj/gimp-2-10/modules/color-selector-water.c:486
#5 0x7fe92a705e91 in _gtk_marshal_BOOLEAN__BOXED /home/massimo/devel/obj/gtk-2-24/gtk/gtkmarshalers.c:84
#6 0x7fe9264c1d8c in g_closure_invoke /home/massimo/devel/obj/glib/gobject/gclosure.c:810