+ * @brief Returns the list of sliding transition/effect names available, for a
+ * given slideshow widget.
+ *
+ * @remarks The transitions, which come from the @a obj theme, must be an EDC
+ * data item named @c "transitions" on the theme file, with (prefix)
+ * names of EDC programs actually implementing them.
+ *
+ * @remarks The available transitions for slideshows on the default theme are:
+ * - @c "fade" - The current item fades out, while the new one
+ * fades in to the slideshow's viewport.
+ * - @c "black_fade" - The current item fades to black, and just
+ * then, the new item fades in.
+ * - @c "horizontal" - The current item slides horizontally, until
+ * it gets out of the slideshow's viewport, while the new item
+ * comes from the left to take its place.
+ * - @c "vertical" - The current item slides vertically, until it
+ * gets out of the slideshow's viewport, while the new item comes
+ * from the bottom to take its place.
+ * - @c "square" - The new item starts to appear from the middle of
+ * the current one, but with a tiny size, growing until its
+ * target (full) size and covering the old one.
+ *
+ * @remarks The stringshared strings get no new references
+ * exclusive to the user grabbing the list, here, so if you would like
+ * to use them out of this call's context, you would better
+ * eina_stringshare_ref() them. Also the list is an internal list and
+ * is only valid for as long as the slideshow object is valid, and
+ * has not internally changed its list for some reason, so make a
+ * copy if you need it.
+ *
+ * @param[in] obj The slideshow object