Fix a scan pop-up for Mac OS

[senseofeternity]

Hello! The scan pop-up feature is not working on Mac OS at the moment. However, it works perfectly within the following build of Goldendict for Mac: https://github.com/yozhic/goldendict-macos-builds
In this regard, is it possible to fix it in Goldendict-ng as well? Thanks!