Main window: Fix "no scanner found" popup
(backport of 37752fe98412e0d54b102819899ef93f7d951d9f)

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
popups: fix depreciation warnings
(backport of 6bd73a403630297539400501eb8e807eca2eb925)

Signed-off-by: Jerome Flesch <jflesch@gmail.com>