I detected several undeclared functions used by gtkhtml. Although gcc only warns about it, it might cause crashes on 64bits platforms because gcc assumes that the return value is an integer(32bits) but sometimes the return value is a pointer (64bits).

Here are the missing functions (extract from build log):

editor-control-factory.c:251: warning: implicit declaration of function 'gtk_html_filename_from_uri'
editor-control-factory.c:251: warning: assignment makes pointer from integer without a cast
image.c:396: warning: implicit declaration of function 'gtk_file_chooser_set_preview_active'

I searched for the function gtk_file_chooser_set_preview_active but didn't found it. I think the right name is gtk_file_chooser_set_preview_widget_active

I'll provide a patch to fix this bug