@prachiz Apologies 😐. I couldn't be of much help here. as I mentioned din reply its been quite a long time I am out of touch with xtypes and classic UI . Hope you get help soon.
Also a recommendation, put a note to your architects or business leads to get the dialog converted to Touch UI. If you are using HTL with Sling models , then you might not have much work to do there , but else if your code is also in JSP, then you might have a bit more work, but trust me it is worth the effort ✌