implement GetWindowPlacement

[LinusU]

Opening this to get some discussion around how to implement variable length structs 🤔

According to MSDN:

[...] Before calling GetWindowPlacement, set the length member to sizeof(WINDOWPLACEMENT). GetWindowPlacement fails if lpwndpl->length is not set correctly.

ref

The problem is that my program (Pocoman) doesn't seem to initialize the length property at all. From looking at Ghidra I think that the variable simply isn't initialized at all, so it has the value of whatever happened to be in that stack position previously. (note that I don't have much experience with this so I could absolutely be wrong)

Here is what dbg!(&wndpl); prints:

&wndpl = WINDOWPLACEMENT {
    length: 50078,
    flags: 4265673,
    showCmd: 4379564,
    ptMinPosition: POINT {
        x: 4260799,
        y: 4,
    },
    ptMaxPosition: POINT {
        x: 4,
        y: 4,
    },
    rcNormalPosition: RECT {
        left: 0,
        top: 50078,
        right: 4247973,
        bottom: 1183232,
    },
    rcDevice: RECT {
        left: 63,
        top: 5,
        right: 16,
        bottom: 4194304,
    },
}

I'm not really sure what to do here. I'm guessing that the input characteristics of length was introduced in a later version, in order to add rcDevice in a backwards compatible way. But I don't understand how that could be since presumable it has been called with uninitialized data for length before that 🤔

[evmar]

I think for now it's fine to just assume it's the size we expect, it looks like wine does this anyway. But I'd fill in length anyway just to be sure.

[LinusU]

@evmar Updated 👍

it seems like the larger size (rcDevice field) is only for old (pre-intel) Mac 😅