www.wysiwygwebbuilder.com

I thought that there used to be a section in the Toolbox for jQuery UI controls? or in the insert ribbon menu but I'm not seeing them in either place.

Looks like there should be a section for jQuery in the ToolBox:
https://www.wysiwygwebbuilder.com/jqueryui_widgets.html

Or I'm just getting senile?

Most of the widgets have been moved to different categories because they are no longer specific to jQuery UI.
The widgets have been redesigned to also use Bootstrap or other lightweight alternatives.
For example, accordion and tabs have been moved to the Layout category. Form specific widgets have been moved to the 'form' category.

Ok now I understand.
Good news is I'm not senile yet

Thanks Pablo