Microsoft did with VBX, OLE and later ActiveX, the entire point was to have embeddable reusable UIs. They sabotaged themselves by tying those to separate produc

Microsoft did with VBX, OLE and later ActiveX, the entire point was to have embeddable reusable UIs. They sabotaged themselves by tying those to separate products you had to buy though instead of having a simple drag-and-drop form/window designer to put things - basically something like the QBasic equivalent of Visual Basic but also closer to the original idea of VB1 where instead of writing basic code you'd drag connections between controls to activate methods or pipe data between them. X11 supports this by allowing programs to "swallow" each other - the XEmbed protocol as well as normal IPC can be used for communication between them. Older desktop environments and window managers (CDE, FVWM, etc) can use this to compose programs. Some minimalistic window managers rely on this using single-purpose tools like dmenu. BeOS, as mentioned elsewhere also has a very limited form of OLE-like functionality. I'm sure there are others but TBH i think MS came closest, but they abandoned the entire idea after they decided to focus on .NET. FWIW the underlying tech is still there and in theory such QB-like-VB-lite app could be made but nothing really exposes reusable controls anymore so it'd be pointless. After all having the tech and ability is only half the battle at most, you also need applications to support it and nowadays everything GUI is made to be cross platform agnostic so any such solution would need to work everywhere there is a monitor, a keyboard and a mouse - not impossible but much harder nowadays than when computers were synonymous with Windows.