This started occurring after 4.7.0-tp1. I've noticed it with 2 native dialogs Open Files and Open Folder (the only ones I use). I tried to debug the issue and found that IModalWindow::Show returns HRESULT 0x800704c7, which to my knowledge is ERROR_CANCELLED "The operation was canceled by the user." though I have no idea why. The parent window loses focus, the dialog does not appear and the parent window regains focus.

IModalWindow::Show is called from qt_win_CID_get_open_file_names and qt_win_CID_get_existing_directory. I use QFileDialog::getOpenFileNames and QFileDialog::getExistingDirectory to open the dialogs.

Non-native dialogs, opened with the QFileDialog::DontUseNativeDialog flag open and work correctly.