Yad (yet another dialog) is a fork of Zenity with many improvements, such as custom buttons, additional dialogs, pop-up menu in notification icon and more.
There were two main reasons to make this fork. The first one is to remove dependencies on deprecated libraries, such as libglade and gnome-canvas. And the second one - as for me, Zenity looks like an abandoned project. Its ChangeLog consists of just "bump version to..." and "translation updated" for the long time, but many interesting ideas which are ignored by developers/maintainers were in GNOME Bugzilla.
Thanks for taking the time to discuss this, I feel strongly about it and love learning more on this topic. If possible, as you gain expertise, would you mind updating your blog with extra information? It is extremely helpful for me. liteblue usps gov