“dia” is a german word for “Reversal film”.
This is a small dockapp, which does nearly nothing. It just creates an empty window with a 62x62 background pixmap.
When you click on the window, the command in the property “COMMAND” is executed. When you move the mouse in the window the text in the property “TOOLTIP” is shown as tooltip.
For comments, see the original dockapps.org entry.