4 files changed, 37 insertions, 8 deletions
diff --git a/src/plugins/platforms/cocoa/qcocoaglcontext.mm b/src/plugins/platforms/cocoa/qcocoaglcontext.mm
index adad12a4242..be05249c1b8 100644
--- a/src/plugins/platforms/cocoa/qcocoaglcontext.mm
+++ b/src/plugins/platforms/cocoa/qcocoaglcontext.mm
@@ -265,19 +265,26 @@ void QCocoaGLContext::updateSurfaceFormat()
         return value;
     };
 
-    int colorSize = pixelFormatAttribute(NSOpenGLPFAColorSize);
-    colorSize /= 4; // The attribute includes the alpha component
-    m_format.setRedBufferSize(colorSize);
-    m_format.setGreenBufferSize(colorSize);
-    m_format.setBlueBufferSize(colorSize);
+    // Resolve color channel bits from GL, rather than NSOpenGLPFAColorSize,
+    // as the latter is not specific enough (combines all channels).
+    GLint redBits, greenBits, blueBits;
+    glGetIntegerv(GL_RED_BITS, &redBits);
+    glGetIntegerv(GL_GREEN_BITS, &greenBits);
+    glGetIntegerv(GL_BLUE_BITS, &blueBits);
+    m_format.setRedBufferSize(redBits);
+    m_format.setGreenBufferSize(greenBits);
+    m_format.setBlueBufferSize(blueBits);
 
     // Surfaces on macOS always have an alpha channel, but unless the user requested
     // one via setAlphaBufferSize(), which triggered setting NSOpenGLCPSurfaceOpacity
     // to make the surface non-opaque, we don't want to report back the actual alpha
     // size, as that will make the user believe the alpha channel can be used for
     // something useful, when in reality it can't, due to the surface being opaque.
-    if (m_format.alphaBufferSize() > 0)
-        m_format.setAlphaBufferSize(pixelFormatAttribute(NSOpenGLPFAAlphaSize));
+    if (m_format.alphaBufferSize() > 0) {
+        GLint alphaBits;
+        glGetIntegerv(GL_ALPHA_BITS, &alphaBits);
+        m_format.setAlphaBufferSize(alphaBits);
+    }
 
     m_format.setDepthBufferSize(pixelFormatAttribute(NSOpenGLPFADepthSize));
     m_format.setStencilBufferSize(pixelFormatAttribute(NSOpenGLPFAStencilSize));
diff --git a/src/plugins/platforms/windows/qwindowsscreen.cpp b/src/plugins/platforms/windows/qwindowsscreen.cpp
index 0236669d6fb..23bbe409caa 100644
--- a/src/plugins/platforms/windows/qwindowsscreen.cpp
+++ b/src/plugins/platforms/windows/qwindowsscreen.cpp
@@ -450,6 +450,26 @@ QPixmap QWindowsScreen::grabWindow(WId window, int xIn, int yIn, int width, int
         hwnd = GetDesktopWindow();
         const QRect screenGeometry = geometry();
         windowSize = screenGeometry.size();
+        // When dpi awareness is not set to PerMonitor, windows reports primary display or dummy
+        // DPI for all displays, so xIn and yIn and windowSize are calculated with a wrong DPI,
+        // so we need to recalculate them using the actual screen size we get from
+        // EnumDisplaySettings api.
+        const auto dpiAwareness = QWindowsContext::instance()->processDpiAwareness();
+        if (dpiAwareness != QtWindows::DpiAwareness::PerMonitor &&
+            dpiAwareness != QtWindows::DpiAwareness::PerMonitorVersion2) {
+            MONITORINFOEX info = {};
+            info.cbSize = sizeof(MONITORINFOEX);
+            if (GetMonitorInfo(handle(), &info)) {
+                DEVMODE dm = {};
+                dm.dmSize = sizeof(dm);
+                if (EnumDisplaySettings(info.szDevice, ENUM_CURRENT_SETTINGS, &dm)) {
+                    qreal scale = static_cast<qreal>(dm.dmPelsWidth) / windowSize.width();
+                    x = static_cast<int>(static_cast<qreal>(x) * scale);
+                    y = static_cast<int>(static_cast<qreal>(y) * scale);
+                    windowSize = QSize(dm.dmPelsWidth, dm.dmPelsHeight);
+                }
+            }
+        }
         x += screenGeometry.x();
         y += screenGeometry.y();
     }
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index b77e985c965..2816982b1a8 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -1732,8 +1732,10 @@ void QWindowsWindow::destroyWindow()
             m_surface = nullptr;
         }
 #endif
+        DestroyWindow(m_data.hwndTitlebar);
         DestroyWindow(m_data.hwnd);
         context->removeWindow(m_data.hwnd);
+        m_data.hwndTitlebar = nullptr;
         m_data.hwnd = nullptr;
     }
 }
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 2c56603fef0..7d5f0155960 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -2573,7 +2573,7 @@ void QXcbWindow::setOpacity(qreal level)
     if (!m_window)
         return;
 
-    quint32 value = qRound64(qBound(qreal(0), level, qreal(1)) * 0xffffffff);
+    quint32 value = qRound64(qBound(qreal(0), level, qreal(1)) * qreal(0xffffffff));
 
     xcb_change_property(xcb_connection(),
                         XCB_PROP_MODE_REPLACE,