Fix more qt6 compat

Signed-off-by: falkTX <falktx@falktx.com>

source/frontend/qt_compat.py

@@ -218,9 +218,15 @@ elif qt_config == 6:
 
     QMessageBox.exec_ = lambda mb: mb.exec()
 
+    QMessageBox.Cancel = QMessageBox.StandardButton.Cancel
     QMessageBox.No = QMessageBox.StandardButton.No
+    QMessageBox.Ok = QMessageBox.StandardButton.Ok
     QMessageBox.Yes = QMessageBox.StandardButton.Yes
 
+    QMessageBox.Critical = QMessageBox.Icon.Critical
+    QMessageBox.Information = QMessageBox.Icon.Information
+    QMessageBox.Warning = QMessageBox.Icon.Warning
+
     QPainter.CompositionMode_Difference = QPainter.CompositionMode.CompositionMode_Difference
     QPainter.CompositionMode_Multiply = QPainter.CompositionMode.CompositionMode_Multiply
     QPainter.CompositionMode_Plus = QPainter.CompositionMode.CompositionMode_Plus