Windows QPA: Fix QDockWindow Drag & Drop

Pointer messages should not be handled when we are inside a move/resize
modal loop. DefWindowProc() should handle this case instead.

Fixes: QTBUG-72078
Change-Id: I5ad7283bcf0cfe0ff7d21cf5640270c361b8ad8d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowspointerhandler.cpp b/src/plugins/platforms/windows/qwindowspointerhandler.cpp
index 0bac382a90..14559d726a 100644
--- a/src/plugins/platforms/windows/qwindowspointerhandler.cpp
+++ b/src/plugins/platforms/windows/qwindowspointerhandler.cpp
@@ -187,6 +187,12 @@ static bool draggingActive()
 bool QWindowsPointerHandler::translatePointerEvent(QWindow *window, HWND hwnd, QtWindows::WindowsEventType et, MSG msg, LRESULT *result)
 {
     *result = 0;
+
+    // If we are inside the move/resize modal loop, let DefWindowProc() handle it (but process NC button release).
+    QWindowsWindow *platformWindow = static_cast<QWindowsWindow *>(window->handle());
+    if (msg.message != WM_NCPOINTERUP && platformWindow->testFlag(QWindowsWindow::ResizeMoveActive))
+        return false;
+
     const quint32 pointerId = GET_POINTERID_WPARAM(msg.wParam);
 
     POINTER_INPUT_TYPE pointerType;
@@ -195,6 +201,18 @@ bool QWindowsPointerHandler::translatePointerEvent(QWindow *window, HWND hwnd, Q
         return false;
     }
 
+    // Handle non-client pen/touch as generic mouse events for compatibility with QDockWindow.
+    if ((pointerType == QT_PT_TOUCH || pointerType == QT_PT_PEN) && (et & QtWindows::NonClientEventFlag)) {
+        POINTER_INFO pointerInfo;
+        if (!QWindowsContext::user32dll.getPointerInfo(pointerId, &pointerInfo)) {
+            qWarning() << "GetPointerInfo() failed:" << qt_error_string();
+            return false;
+        }
+        if (pointerInfo.pointerFlags & (POINTER_FLAG_UP | POINTER_FLAG_DOWN))
+            return translateMouseTouchPadEvent(window, hwnd, et, msg, &pointerInfo);
+        return false;
+    }
+
     switch (pointerType) {
     case QT_PT_POINTER:
     case QT_PT_MOUSE: