QtIFW

fix designer warning

  - MessageBoxHandler::currentBestSuitParent() is a QWizard in most cases
    and then it tries to add QWidgets to it, but it allows only QWizardPage
  - this results in a memory leak of the translatewatch objects inside the
    loader, but needs to be fixed in the QUiLoader see QTBUG-31818

Change-Id: I67b0cc78c3843d4bbe70f015a63b5c26bb7f9e2c
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>