[pjmlp]

I mean using a static C++ lambda that moves the context into the lambda body via capture specifier.

C++ lambdas are basically old style C++ functors that are compiled generated, with the calling address being the operator().

[rovingeye]

That doesn't sound like a valid wndproc

[pjmlp]

It certainly is,

https://github.com/pjmlp/LambdaWndProc/blob/main/LambdaWndPr...

[rovingeye]

It looks like you missed the part where you "move the context into the lambda body via capture specifier."