Parent window is still responsive when child window opens

rahman110

Pretty new to Qt, I am developing a simple GUI DLL for db driver configuration in Windows.

First, the situation. I am improving an ODBC driver.
Windows ODBC Administrator allows you to write a GUI get configs from the user, and puts them into the registry.
We just have to create a DLL, and export the function ConfigDSN:

BOOL CALLBACK
ConfigDSN(
         HWND hwndParent,    // Parent window handle
         WORD fRequest, LPCSTR driver_desc,  LPCSTR connect_str)
{
    int argc = 0;
    char *argv[] = {nullptr};
    QApplication app(argc, argv);

    MyWidget widget;
    SetWindowLongPtr((HWND)widget.winId(), GWLP_HWNDPARENT, (LONG_PTR)hwnd);
    EnableWindow(hwnd, FALSE);
    widget.setWindowModality(Qt::WindowModality::ApplicationModal);// same issue with Qt::WindowModality::WindowModal
    widget.show();
    int result = app.exec();
    // Re-enable the parent window when the dialog is closed
    if (hwnd) {
        EnableWindow(hwnd, TRUE);
        SetForegroundWindow(hwnd);  // Bring the parent window to the front
    }
    return result == 0;
}

As youmay see above, I have created an empty form MyWidget which I can open via ODBC Administrator.
I tried several combinations but the problem is, after opening the window:
The parent ODBC Administrator window size and location changes. And, it is still responsive to my clicks while it shouldn't be so until I close MyWidget.
How can I fix this?

Here is my CMakeLists.txt if it helps:

cmake_minimum_required(VERSION 3.16)

project(odbcsetup LANGUAGES CXX)

set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
list(APPEND CMAKE_PREFIX_PATH "C:\\Qt\\6.8.0\\msvc2022_64\\lib\\cmake")
find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Widgets)
find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Widgets)
set(TARGET_NAME "odbcsetup")
add_library(${TARGET_NAME} SHARED
  odbcsetup_global.h
  dsngui.cpp
  dsngui.h
  DsnSetup.cpp DsnSetup.h
  dsnform.h dsnform.cpp dsnform.ui

)

target_link_libraries(${TARGET_NAME} PRIVATE Qt${QT_VERSION_MAJOR}::Widgets)
target_compile_definitions(${TARGET_NAME} PRIVATE ODBC_SETUP_LIBRARY)

# Set the output directories for the target
set_target_properties(
  ${TARGET_NAME}
  PROPERTIES RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/$<CONFIG>"
             LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/$<CONFIG>"
             ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/$<CONFIG>")
install(TARGETS ${TARGET_NAME} DESTINATION "${CMAKE_INSTALL_PREFIX}/lib")

Axel Spoerl

 int result = app.exec();

After that line, the window is no longer visible and hwnd might even contain a stale pointer.

To show a window containing a QWidget, there is no need to call Windows API directly. Doing that is basically asking for trouble.
Remove all win32 calls and use Qt API only.