Which platform to choose for developing a complex cross-platform GUI application?

Question

User interface

There is a task to develop specialized software with a fairly complex GUI. It doesn't matter what to write on, the speed of development is important. A platform (not just a framework) with ready-made GUI elements is needed, on the basis of which this software can be implemented. Cross-platform (Win, Linux, maybe even OS X) and the ability to create complex interfaces are important. A complex interface means not only standard buttons, menus, lists, tables, etc., but the ability to embed a viewport (OpenGL or another 3D API), rotate an interactive 3d model (not real-time rendering, not raytracing), integration with goolge maps / other cards, custom controls.
Is there such a thing or do I have to start from scratch? In the future, I would like to have plugins and some kind of my own / ready-made sdk to expand the capabilities of the program by third-party developers.
Eclipse comes to mind, but there is no experience with it and it is not really clear whether it is possible to do the described on its basis or not.
Please advise or share your experience.
PS Do not offer Delphi :)

Answer 1

Cross-platform (Win, Linux, maybe even OS X) and the ability to create complex interfaces are important.

Python + PyQt
Eclipse is a development environment designed primarily for Java development, which is also a good option. Surely Swing is capable of everything that interests you.

Answer 2

I'm afraid you won't find anything suitable for Delphi. With a stretch, lazarus is suitable, but it (like Delphi in general) is the last century.
In general, delphi for industrial use is now of little use.
For cross-platform, Qt + C++ is better, but there is some speed and development loss.

Answer 3

Thanks for answers.
Found this - https://platform.netbeans.org/screenshots.html
The list of projects is impressive, as are the organizations using the platform.