Option to design standalone UI elements that can be easily added to an existing UI

Similar question was asked here: Loading screens from SD card - #3 by Thomas1955 and V1.4.0 CPU usage is too high )
I tested the manual solution there as an interim workaround (attached a zipped example V1.4.0 CPU usage is too high - #2 by Hermit), this feature-request is already on the list of tasks to do.