Frameless windows window while still using window manager

[xomz]

I am trying to make my QML window become borderless on windows while still using the native window manager to support platform features like aero. I found "a stackoverflow answer":http://stackoverflow.com/a/17713810/2282732 which explains how to do it with win api and tried to use it in Qt.

@#ifndef FRAMELESSWINDOW_H
#define FRAMELESSWINDOW_H

#include <QQuickWindow>
#include <QDebug>
#include <Windows.h>
#include <windowsx.h>

class FramelessWindow : public QQuickWindow {
public:
FramelessWindow(QQuickWindow *parent = 0) : QQuickWindow(parent) {
hwnd = (HWND) this->winId();

    //setFlags(flags() | Qt::FramelessWindowHint);

    LONG lStyle = GetWindowLong(hwnd, GWL_STYLE);
    lStyle = (WS_POPUP | WS_CAPTION | WS_THICKFRAME | WS_MAXIMIZEBOX | WS_MINIMIZEBOX);
    SetWindowLong(hwnd, GWL_STYLE, lStyle);

    LONG lExStyle = GetWindowLong(hwnd, GWL_EXSTYLE);
    lExStyle &= ~(WS_EX_DLGMODALFRAME | WS_EX_CLIENTEDGE | WS_EX_STATICEDGE);
    SetWindowLong(hwnd, GWL_EXSTYLE, lExStyle);
}

private:
HWND hwnd;

long NCHITTEST(LPARAM &lparam) {
    const LONG border_width = 8; //in pixels
    RECT winrect;
    GetWindowRect(hwnd, &winrect);
    long x = GET_X_LPARAM(lparam);
    long y = GET_Y_LPARAM(lparam);

    //bottom left corner
    if (x >= winrect.left && x < winrect.left + border_width &&
        y < winrect.bottom && y >= winrect.bottom - border_width)
    {
        return HTBOTTOMLEFT;
    }
    //bottom right corner
    if (x < winrect.right && x >= winrect.right - border_width &&
        y < winrect.bottom && y >= winrect.bottom - border_width)
    {
        return HTBOTTOMRIGHT;
    }
    //top left corner
    if (x >= winrect.left && x < winrect.left + border_width &&
        y >= winrect.top && y < winrect.top + border_width)
    {
        return HTTOPLEFT;
    }
    //top right corner
    if (x < winrect.right && x >= winrect.right - border_width &&
        y >= winrect.top && y < winrect.top + border_width)
    {
        return HTTOPRIGHT;
    }
    //left border
    if (x >= winrect.left && x < winrect.left + border_width)
    {
        return HTLEFT;
    }
    //right border
    if (x < winrect.right && x >= winrect.right - border_width)
    {
        return HTRIGHT;
    }
    //bottom border
    if (y < winrect.bottom && y >= winrect.bottom - border_width)
    {
        return HTBOTTOM;
    }
    //top border
    if (y >= winrect.top && y < winrect.top + border_width)
    {
        return HTTOP;
    }

    return HTCAPTION;
}

bool nativeEvent(const QByteArray &eventType, void *message, long *result) {
    MSG* msg = (MSG*) message;
    switch(msg->message) {
    case WM_NCCALCSIZE:
        *result = 0;
        return true;
        break;
    case WM_NCHITTEST:
        *result = NCHITTEST(msg->lParam);
        return true;
    }
    return false;
}

};

#endif // FRAMELESSWINDOW_H
@

However in general it works but the window has a margin of 8 + 8 px on the right (the windows frame is 8 px thick) and a margin of about 30px on the top (titlebar + bottom border height) which is client aera but gets ignored by Qt.

Screenshot:
!http://i.imgur.com/qoGOPfa.png?1(The squares should be on the edges)!

When I add the Qt::FramelessWindowHint flag the margins disappear and everything is fine until I minimize and restore the window or maximize it (then the margins appear again).

Can somebody help me with this please?