For me it was HyperCard/Runtime Revolution/Livecode.
Unfortunately, that latter, after stumping for funds to go opensource has gone closed source and is now charging enough that I can't justify it for hobbyist use, and the openxtalk folks don't seem to have an easy Windows download yet (I'd love to be wrong).
I'd really like for there to be an opensource successor to VisualBasic which was cross-platform and worked well enough to be popular enough to achieve a critical mass of usage/support.
Check out https://avaloniaui.net as well. It's basically a cross-platform reimplementation of WPF. It's not quite as simple as C#+WinForms or Lazarus+LCL because you don't get drag-and-drop UI designer, and you need to write markup by hand (albeit with live preview). But unlike HTML, it's actually designed for desktop UI apps from the get go, so it's much easier to write for anything non-trivial. And you can still write "quick and dirty" GUI code by directly connecting event handlers to buttons and updating values etc in it, ignoring data bindings and other more advanced facilities.
Unfortunately, that latter, after stumping for funds to go opensource has gone closed source and is now charging enough that I can't justify it for hobbyist use, and the openxtalk folks don't seem to have an easy Windows download yet (I'd love to be wrong).
I'd really like for there to be an opensource successor to VisualBasic which was cross-platform and worked well enough to be popular enough to achieve a critical mass of usage/support.