It’s not so much the case that Opto22 can’t write the code to come up with the functionality you want, its the fact that it has to be pure HTML5 to run on any device and any browser. Most list control is orientating you to a specific web programming tool, platform or browser
Assuming that Opto22 are not going to come up with pulldown boxes anytime soon, maybe some thinking outside the box is required here. I agree that hundreds of grid gadgets that need selecting on or off in order to try and create a schedule program is not going to fit nicely into a groov display, but have you considered using the power of Node-RED to add the intelligence that you are looking for in groov and using groov DataStores to provide the connection between Node-RED and the groov operator display?
Node-RED does have some nice dashboard tools, including pull down select lists. Example in the below screenshot. Batch Selector > Formula1, Formula2, Formula3
Once you set up a Node-RED dashboard you can link it to a Page Navigator gadget in groov VIEW
Finally, don’t forget to include a page link in the Node-RED dashboard menu to lead you back to the safety of a groov VIEW page or you will be stuck in the depths of hell of Node-RED dashboard displays, which is not a very nice place to be!
Also, note that creating Node-RED dashboards is mainly used today as a form of medieval punishment for people who complain about groov VIEW capabilities !!!