I would like to create a geoprocessing tool with a custom GUI for its input data. To put it in other words: imagine that your client works mainly with arcmap documents and he already has an arcpy script which deals with the geoprocessing. Unfortunately he doesn't like building blocks which take parameters for the script (drop-down list, onelineinput etc.) and would like to have a custom input method like let's say a scrollbar (f.e. for selecting time interval instead of typing it manually or selecting from a list).
Is it achievable in ArcMap to have custom input GUI elements? I'm pretty sure it's not, but my colleague swears on everything that he's seen something like that.
Before I completely cross out that idea I wanted to have a confirmation from people who have spent more time working with ArcGIS. To my understanding the only solution is to create a standalone application using Runtime SDK or ArcObjects/ArcEngine.