Do you think object oriented languages are better than C to develop GUI-based cross-platform programs?

The licenses of the majority of third-party libraries available for C are GPL, do you think this makes harder reusing code to sell software?

1. What is the easiest way to build cross-platform (native) GUI with C?

2. Why it is harder to find lgpl licenced libraries to access windows directories over network like jcifs pysmb (and libraries overall) when needed to close most part of software source to sell small softwares to businesses?

3. If you needed to combo C with another language to do everything you need to do forever and never look back what other language would that be?