Index: extobj.h
===================================================================
--- extobj.h	(revision 11165)
+++ extobj.h	(revision 11166)
@@ -33,6 +33,7 @@
 	void (*attr_edit_post)(csch_cgrp_t *grp, const char *key);    /* called after an attribute change */
 	void (*update)(csch_cgrp_t *grp);       /* recompute graphics */
 	void (*gui_edit_dlg)(csch_cgrp_t *grp); /* present the object-specific editor dialog */
+	void (*conv_from)(vtp0_t *objs);        /* remove one or more objects from objs and convert them into extended object(s) */
 };
 
 void csch_extobj_impl_reg(const csch_extobj_impl_t *impl);
@@ -51,6 +52,11 @@
    present. Returns 0 on success (dialog invoked). */
 RND_INLINE int csch_extobj_gui_edit_dlg(csch_cgrp_t *grp);
 
+
+/* Convert objects to extended object of type eo. All objects in objs shall
+   be on the same sheet. Object converted are removed from objs. */
+void csch_extobj_conv_from(vtp0_t *objs, const csch_extobj_impl_t *eo);
+
 /*** for implementing extended objects ***/
 
 /* return the extobj-gfx group within grp or NULL if not found */