If you don't want to use frameworks like qt, wxWidgets, then you'll have to either:

1. Use the platform windowing API (WINAPI, XLib, Cocoa).
2. Write your own widget toolkit and render it yourself using OpenGL/DirectX.

There is no pleasant way around this. (1) is massive pain in the ass. (2) is less pain in the ass, and allows to implement custom game specific widgets easier, but is massive amount of work nevertheless.

What lazy game developers do:

1. Use WinForms + C# and render into a OpenGLControl / DirectX widget.
2. Create small, incomplete IMGUI lib or use existing "Dear Imgui" (with C++).
3. Use Qt, and render into DX/OpenGL widget
4. Use UI tools in engines (Unity has IMGUI).

Or some variations on this.

The times of easy RAD/WYSIWYG UI programming - in the spirit of Delphi - are essentially dead (WinForms kind of provides similar experience, but is kind of dated).

Looks like Capcom's MT Framework has done (2) - implemented their own widget toolkit (which they render themselves). It doesn't look very pretty (monospaced bitmap fonts!). Excuse the JPG artifacts.

If you don't want to use frameworks like qt, wxWidgets, then you'll have to either:

1. Use the platform windowing API (WINAPI, XLib, Cocoa).
2. Write your own widget toolkit and render it yourself using OpenGL/DirectX.

There is no pleasant way around this. (1) is massive pain in the ass. (2) is less pain in the ass, and allows to implement custom game specific widgets easier, but is massive amount of work nevertheless.

What lazy game developers do:

1. Use WinForms + C# and render into a OpenGLControl / DirectX widget.
2. Create small, incomplete IMGUI lib or use existing "Dear Imgui" (with C++).
3. Use Qt, and render into DX/OpenGL widget
4. Use UI tools in engines (Unity has IMGUI).

Or some variations on this.

The times of easy RAD/WYSIWYG UI programming - in the spirit of Delphi - are essentially long gone (WinForms kind of provides similar experience, but is kind of dated).

Looks like Capcom's MT Framework has done (2) - implemented their own widget toolkit (which they render themselves). It doesn't look very pretty (monospaced bitmap fonts!). Excuse the JPG artifacts.

Some first party Sony devs use https://github.com/SonyWWS/ATF. Which is WinForms+C# for UI and C++ engine interop stuff. Not quite pretty either.

There is no easy way.

If you don't want to use frameworks like qt, wxWidgets, then you'll have to either:

1. Use the platform windowing API (WINAPI, XLib, Cocoa).
2. Write your own widget toolkit and render it yourself using OpenGL/DirectX.

There is no pleasant way around this. (1) is massive pain in the ass. (2) is less pain in the ass, and allows to implement custom game specific widgets easier, but is massive amount of work nevertheless.

What lazy game developers do:

1. Use WinForms + C# and render into a OpenGLControl / DirectX widget.
2. Create small, incomplete IMGUI lib or use existing "Dear Imgui" (with C++).
3. Use Qt, and render into DX/OpenGL widget
4. Use UI tools in engines (Unity has IMGUI).

Or some variations on this.

The times of easy RAD/WYSIWYG UI programming - in the spirit of Delphi - are essentially dead (WinForms kind of provides similar experience, but is kind of dated).

If you don't want to use frameworks like qt, wxWidgets, then you'll have to either:

1. Use the platform windowing API (WINAPI, XLib, Cocoa).
2. Write your own widget toolkit and render it yourself using OpenGL/DirectX.

There is no pleasant way around this. (1) is massive pain in the ass. (2) is less pain in the ass, and allows to implement custom game specific widgets easier, but is massive amount of work nevertheless.

What lazy game developers do:

1. Use WinForms + C# and render into a OpenGLControl / DirectX widget.
2. Create small, incomplete IMGUI lib or use existing "Dear Imgui" (with C++).
3. Use Qt, and render into DX/OpenGL widget
4. Use UI tools in engines (Unity has IMGUI).

Or some variations on this.

The times of easy RAD/WYSIWYG UI programming - in the spirit of Delphi - are essentially dead (WinForms kind of provides similar experience, but is kind of dated).

Looks like Capcom's MT Framework has done (2) - implemented their own widget toolkit (which they render themselves). It doesn't look very pretty (monospaced bitmap fonts!). Excuse the JPG artifacts.