Well, it's not something that's provided by Qt out of the box, so you'll have to check the platforms you want to support for how they provide that information.

You could even consider contributing that to Qt to improve it for everybody.

You might also open a feature request on the bug report system for that.

here is the solution:
https://forum.qt.io/topic/76802/how-to-enable-virtual-keyboard-languages/5

Thank you all,
I am going to mark this discussion as solved;
However, Any more comments would be much appreciated;

I think MikePelton is long gone but nevertheless I would like to thank him for his contribution.

I was caught out by this today. I always use the 'INS' on the numeric pad to toggle insert/overstrike - in other editors at least - so was a bit baffled as to how to get back to insert mode. As noted by Mike, the separate INSERT key does work.